Liberty Reference Manual (Version 2007.03)

1. Technology Library Group Description and Syntax

1.1 Library-Level Attributes and Values

1.2 General Syntax

1.3 Reducing Library File Size

1.4 library Group Name

1.4.1 Syntax

1.4.2 Example

1.5 library Group Example

1.6 Simple Attributes

1.6.1 bus_naming_style Simple Attribute

1.6.2 comment Simple Attribute

1.6.3 current_unit Simple Attribute

1.6.4 date Simple Attribute

1.6.5 default_fpga_isd Simple Attribute

1.6.6 default_threshold_voltage_group Simple Attribute

1.6.7 delay_model Simple Attribute

1.6.8 em_temp_degradation_factor Simple Attribute

1.6.9 fpga_domain_style Simple Attribute

1.6.10 fpga_technology Simple Attribute

1.6.11 in_place_swap_mode Simple Attribute

1.6.12 input_threshold_pct_fall Simple Attribute

1.6.13 input_threshold_pct_rise Simple Attribute

1.6.14 leakage_power_unit Simple Attribute

1.6.15 nom_calc_mode Simple Attribute

1.6.16 nom_process Simple Attribute

1.6.17 nom_temperature Simple Attribute

1.6.18 nom_voltage Simple Attribute

1.6.19 output_threshold_pct_fall Simple Attribute

1.6.20 output_threshold_pct_rise Simple Attribute

1.6.21 piece_type Simple Attribute

1.6.22 power_model Simple Attribute

1.6.23 preferred_output_pad_slew_rate_control Simple Attribute

1.6.24 preferred_input_pad_voltage Simple Attribute

1.6.25 preferred_output_pad_voltage Simple Attribute

1.6.26 pulling_resistance_unit Simple Attribute

1.6.27 revision Simple Attribute

1.6.28 simulation Simple Attribute

1.6.29 slew_derate_from_library Simple Attribute

1.6.30 slew_lower_threshold_pct_fall Simple Attribute

1.6.31 slew_lower_threshold_pct_rise Simple Attribute

1.6.32 slew_upper_threshold_pct_fall Simple Attribute

1.6.33 slew_upper_threshold_pct_rise Simple Attribute

1.6.34 time_unit Simple Attribute

1.6.35 voltage_unit Simple Attribute

1.7 Defining Default Attribute Values in a CMOS Technology Library

1.8 Complex Attributes

1.8.1 capacitive_load_unit Complex Attribute

1.8.2 default_part Complex Attribute

1.8.3 define Complex Attribute

1.8.4 define_cell_area Complex Attribute

1.8.5 define_group Complex Attribute

1.8.6 library_features Complex Attribute

1.8.7 piece_define Complex Attribute

1.8.8 routing_layers Complex Attribute

1.8.9 technology Complex Attribute

1.8.10 voltage_map Complex Attribute

1.9 Group Statements

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1.9.1 base_curves Group

1.9.2 base_curve_type Complex Attribute

1.9.3 curve_x Complex Attribute

1.9.4 curve_y Complex Attribute

1.9.5 compact_lut_template Group

1.9.6 base_curves_group Simple Attribute

1.9.7 variable_1 and variable_2 Simple Attributes

1.9.8 variable_3 Simple Attribute

1.9.9 index_1 and index_2 Complex Attributes

1.9.10 index_3 Complex Attribute

1.9.11 dc_current_template Group

1.9.12 em_lut_template Group

1.9.13 fall_net_delay Group

1.9.14 fall_transition_degradation Group

1.9.15 faults_lut_template

1.9.16 input_voltage Group

1.9.17 fpga_isd Group

1.9.18 iv_lut_template Group

1.9.19 lu_table_template Group

1.9.20 maxcap_lut_template Group

1.9.21 maxtrans_lut_template Group

1.9.22 noise_lut_template Group

1.9.23 normalized_driver_waveform Group

1.9.24 operating_conditions Group

1.9.25 output_current_template Group

1.9.26 output_voltage Group

1.9.27 part Group

1.9.28 pg_current_template Group

1.9.29 poly_template Group

1.9.30 power_lut_template Group

1.9.31 power_poly_template Group

1.9.32 power_supply Group

1.9.33 propagation_lut_template Group

1.9.34 rise_net_delay Group

1.9.35 rise_transition_degradation Group

1.9.36 scaled_cell Group

1.9.37 sensitization Group

1.9.38 pin_names Complex Attribute

1.9.39 vector Complex Attribute

1.9.40 scaling_factors Group

1.9.41 timing Group

1.9.42 timing_range Group

1.9.43 type Group

1.9.44 user_parameters Group

1.9.45 wire_load Group

1.9.46 wire_load_selection Group

1.9.47 wire_load_table Group

2. cell and model Group Description and Syntax

2.1 cell Group

2.1.1 Attributes and Values

2.1.2 Simple Attributes

2.1.3 Complex Attributes

2.1.4 Group Statements

2.2 model Group

2.2.1 Attributes and Values

3. pin Group Description and Syntax

3.1 Syntax of a pin Group in a cell or bus Group

3.1.1 pin Group Example

3.1.2 Simple Attributes

3.1.3 Complex Attributes

3.2 Group Statements

3.2.1 ccsn_first_stage Group

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3.2.2 ccsn_last_stage Group

3.2.3 electromigration Group

3.2.4 hyperbolic_noise_above_high Group

3.2.5 hyperbolic_noise_below_low Group

3.2.6 hyperbolic_noise_high Group

3.2.7 hyperbolic_noise_low Group

3.2.8 internal_power Group

3.2.9 max_cap Group

3.2.10 max_trans Group

3.2.11 min_pulse_width Group

3.2.12 minimum_period Group

3.2.13 pin_capacitance Group

3.2.14 receiver_capacitance Group

3.2.15 timing Group in a pin Group

3.2.16 tlatch Group

Index

1. Technology Library Group Description and Syntax

This chapter describes the role of the library group in defining a CMOS technology

library.

The information in this chapter includes a description and syntax example for all the

attributes and groups that you can define within the library group, with the following

exceptions:

● The cell and model groups, which are described in Chapter 2, “cell and model

Group Description and Syntax”

● The pin group, which is described in Chapter 3, “pin Group Description and

Syntax”

This chapter provides information about the library group in the following sections:

● Library-Level Attributes and Values

● General Syntax

● Reducing Library File Size

● library Group Name

● library Group Example

● Simple Attributes

● Defining Default Attribute Values in a CMOS Technology Library

● Complex Attributes

● Group Statements

1.1 Library-Level Attributes and Values

The library group is the superior group in a technology library. The library group

contains all the groups and attributes that define the technology library.

Example 1-1 lists alphabetically a sampling of the attributes, groups, and values that you

can define within a technology library. Example 1-2 shows the general syntax and the

functional order in which the attributes usually appear within a library group.

Example 1-1 Attributes, Groups, and Values in a Technology Library

library (namestring) {

... library description ...

}

/* Library Description: Simple Attributes */

bus_naming_style : "string" ;

comment : "string" ;

current_unit : valueenum ;

date : "date" ;

delay_model : valueenum ;

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em_temp_degradation_factor : float ;

fpga_technology : "fpga_echnology_namestring " ;

in_place_swap_mode : match_footprint | no_swapping ;

input_threshold_pct_fall : trip_point value ;

input_threshold_pct_rise : trip_point value ;

leakage_power_unit : valueenum ;

nom_calc_mode : nameid;

nom_process : float ;

nom_temperature : float ;

nom_voltage : float ;

output_threshold_pct_fall : trip_point value ;

output_threshold_pct_rise : trip_point value ;

piece_type : valueenum ;

power_model : table_lookup | polynomial ;

preferred_output_pad_slew_rate_control : valueenum ;

preferred_input_pad_voltage : string ;

preferred_output_pad_voltage : string ;

pulling_resistance_unit : 1ohm | 10ohm | 100ohm | 1kohm ;

revision : float | string ;

simulation : true | false ;

slew_derate_from_library : derate value ;

slew_lower_threshold_pct_fall : trip_point value ;

slew_lower_threshold_pct_rise : trip_point value ;

slew_upper_threshold_pct_fall : trip_point value ;

slew_upper_threshold_pct_rise : trip_point value ;

time_unit : 1ps | 10ps | 100ps | 1ns ;

voltage_unit : 1mV | 10mV | 100mV | 1V ;

/* Library Description: Default Attributes */

default_cell_leakage_power : float ;

default_connection_class : name | name_liststring ;

default_fall_delay_intercept : float ; /* piecewise model only*/

default_fall_pin_resistance : float ; /* piecewise model only*/

default_fanout_load : float ;

default_inout_pin_cap : float ;

default_inout_pin_fall_res : float ;

default_inout_pin_rise_res : float ;

default_input_pin_cap : float ;

default_intrinsic_fall : float ;

default_intrinsic_rise : float ;

default_leakage_power_density : float ;

default_max_capacitance : float ;

default_max_fanout : float ;

default_max_transition : float ;

default_max_utilization: float ;

default_min_porosity : float ;

default_operating_conditions : namestring ;

default_output_pin_cap : float ;

default_output_pin_fall_res : float ;

default_output_pin_rise_res : float ;

default_rise_delay_intercept : float ; /* piecewise model only */

default_rise_pin_resistance : float ; /* piecewise model only */

default_slope_fall : float ;

default_slope_rise : float ;

default_wire_load : namestring ;

default_wire_load_area : float ;

default_wire_load_capacitance : float ;

default_wire_load_mode : top | segmented | enclosed ;

default_wire_load_resistance : float ;

default_wire_load_selection : namestring ;

/* Library Description: Scaling Attributes */

k_process_cell_fall : float ; /* nonlinear model only */

k_process_cell_leakage_power : float ;

k_process_cell_rise : float ; /* nonlinear model only */

k_process_drive_current : float ;

k_process_drive_fall : float ;

k_process_drive_rise : float ;

k_process_fall_delay_intercept : float ; /* piecewise model only */

k_process_fall_pin_resistance : float ; /* piecewise model only */

k_process_fall_propagation : float ; /* nonlinear model only */

k_process_fall_transition : float ; /* nonlinear model only */

k_process_hold_fall : float ;

k_process_hold_rise : float ;

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k_process_internal_power : float ;

k_process_intrinsic_fall : float ;

k_process_intrinsic_rise : float ;

k_process_min_period : float ;

k_process_min_pulse_width_high : float ;

k_process_min_pulse_width_low : float ;

k_process_nochange_fall : float ; /* nonnegative value */

k_process_nochange_rise: float ; /* nonnegative value */

k_process_pin_cap : float ;

k_process_recovery_fall : float ;

k_process_recovery_rise : float ;

k_process_removal_fall : float ;

k_process_removal_rise : float ;

k_process_rise_delay_intercept : float ; /* piecewise model only */

k_process_rise_pin_resistance : float ; /* piecewise model only */

k_process_rise_propagation : float ; /* nonlinear model only */

k_process_rise_transition : float ; /* nonlinear model only */

k_process_setup_fall : float ;

k_process_setup_rise : float ;

k_process_skew_fall : float ;

k_process_skew_rise : float ;

k_process_slope_fall : float ;

k_process_slope_rise : float ;

k_process_wire_cap : float ;

k_process_wire_res : float ;

k_temp_cell_rise : float ; /* nonlinear model only */

k_temp_cell_fall : float ; /* nonlinear model only */

k_temp_cell_leakage_power : float ;

k_temp_drive_current : float ;

k_temp_drive_fall : float ;

k_temp_drive_rise : float ;

k_temp_fall_delay_intercept : float ; /* piecewise model only */

k_temp_fall_pin_resistance : float ; /* piecewise model only */

k_temp_fall_propagation : float ; /* nonlinear model only */

k_temp_fall_transition : float ; /* nonlinear model only */

k_temp_hold_fall : float ;

k_temp_hold_rise : float ;

k_temp_internal_power : float ;

k_temp_intrinsic_fall : float ;

k_temp_intrinsic_rise : float ;

k_temp_min_period : float ;

k_temp_min_pulse_width_high : float ;

k_temp_min_pulse_width_low : float ;

k_temp_nochange_fall : float ;

k_temp_nochange_rise : float ;

k_temp_pin_cap : float ;

k_temp_recovery_fall : float ;

k_temp_recovery_rise : float ;

k_temp_removal_fall : float ;

k_temp_removal_rise : float ;

k_temp_rise_delay_intercept : float ; /* piecewise model only *

k_temp_rise_pin_resistance : float ; /* piecewise model only */

k_temp_rise_propogation : float /* nonlinear model only */

k_temp_rise_transition : float ; /* nonlinear model only */

k_temp_rise_wire_resistance : float ;

k_temp_setup_fall : float ;

k_temp_rise_wire_resistance : float ;

k_temp_setup_rise : float ;

k_temp_skew_fall : float ;

k_temp_skew_rise : float ;

k_temp_slope_fall : float ;

k_temp_slope_rise : float ;

k_temp_wire_cap : float ;

k_temp_wire_res : float ;

k_volt_cell_fall : float ; /* nonlinear model only */

k_volt_cell_leakage_power : float ;

k_volt_cell_rise : float ; /* nonlinear model only */

k_volt_drive_current : float ;

k_volt_drive_fall: float ;

k_volt_drive_rise : float ;

k_volt_fall_delay_intercept : float ; /* piecewise model only */

k_volt_fall_pin_resistance : float ; /* piecewise model only */

k_volt_fall_propagation : float ; /* nonlinear model only */

k_volt_fall_transition : float ; /* nonlinear model only */

k_volt_hold_fall : float ;

k_volt_hold_rise : float ;

k_volt_internal_power : float ;

k_volt_intrinsic_fall : float ;

k_volt_intrinsic_rise : float ;

k_volt_min_period : float ;

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k_volt_min_pulse_width_high : float ;

k_volt_min_pulse_width_low : float ;

k_volt_nochange_fall : float ;

k_volt_nochange_rise : float ;

k_volt_pin_cap : float ;

k_volt_recovery_fall : float ;

k_volt_recovery_rise : float ;

k_volt_removal_fall : float ;

k_volt_removal_rise : float ;

k_volt_rise_delay_intercept : float ; /* piecewise model only */

k_volt_rise_pin_resistance : float ; /* piecewise model only */

k_volt_rise_propagation : float ; /* nonlinear model only */

k_volt_rise_transition : float ; /* nonlinear model only */

k_volt_setup_fall : float ;

k_volt_setup_rise : float ;

k_volt_skew_fall : float ;

k_volt_skew_rise : float ;

k_volt_slope_fall : float ;

k_volt_slope_rise : float ;

k_volt_wire_cap : float ;

k_volt_wire_res : float ;

/* Library Description: Complex Attributes */

capacitive_load_unit (value, unit) ;

default_part (default_part_nameid, speed_gradeid) ;

define (name, object, type) ; /*user—defined attributes only */

define_cell_area (area_name, resource_type) ;

define_group (attribute_namestring, group_namestring,attribute_typestring ;

library_features (value_1, value_2, ..., value_n) ;

piece_define ("range0 [range1 range2...]") ;

routing_layers ("routing_layer_1_name",...,"routing_layer_n_name") ;

technology ("name") ;

/* Library Description: Group Statements*/

cell (name) { }

dc_current_template (template_nameid) {

em_lut_template (name) { }

fall_net_delay : name ;

fall_transition_degradation (name) { }

faults_lut_template ( name ) { }

input_voltage (name) { }

iv_lut_template(namestring) { }

lu_table_template (name) { }

noise_lut_template (namestring) { }

operating_conditions (name) { }

output_voltage (name) { }

part (name){ }

poly_template (template_nameid ) { }

power_lut_template (template_nameid ) { }

power_poly_template () { }

power_supply () { }

propagation_lut_template (namestring) { }

rise_net_delay : name ;

rise_transition_degradation () { }

scaled_cell (name, op_conds) { }

scaling_factors (name) { }

timing (name | name_list) { }

timing_range (name) { }

type (name) { }

wire_load (name) { }

wire_load_selection (name) { }

wire_load_table (name) { }

1.2 General Syntax

Example 1-2 shows the general syntax of the library group. The first line names the

library. Subsequent lines show simple and complex attributes that apply to the library as a

whole, such as technology, date, and revision.

The example indicates where you place the default and scaling factors in library syntax.

Group statements complete the library syntax.

Every cell in the library has a separate cell description.

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Note:

Example 1-2 does not contain every attribute or group listed in Example 1-1.

Example 1-2 General Syntax of a Technology Library

library (namestring) {

/* Library-Level Simple and Complex Attributes */

technology (nameenum ) ;

delay_model : "model" ;

bus_naming_style : "string" ;

date : "date" ;

comment : "string" ;

time_unit : "unit" ;

voltage_unit : "unit" ;

leakage_power_unit : "unit" ;

current_unit : "unit" ;

pulling_resistance_unit : "unit" ;

capacitive_load_unit (value, unit) ;

piece_type : type ;

piece_define ( "range0 [range1 range2 ...]" ) ;

define_cell_area (area_name, resource_type) ;

revision : float | string ;

in_place_swap_mode : match_footprint | no_swapping ;

simulation : true | false ;

/* Default Attributes and Values (not shown here)*/

/* Scaling Factors Attributes and Values (not shown here)*/

/* Library-Level Group Statements */

operating_conditions (namestring) {

... operating conditions description ...

}

timing_range (namestring) {

... timing range description ...

}

wire_load (namestring) {

... wire load description ...

}

wire_load_selection (namestring) {

... wire load selection criteria...

}

poly_template (namestring) {

... polynomial template information...

}

power_lut_template (namestring) {

... power lookup table template information...

}

power_poly_template (namestring) {

... power polynomial template information...

}

power_supply () {

... power supply information...

}

/* Cell definitions */

cell (namestring2) {

... cell description ...

}

scaled_cell (namestring1) {

... scaled cell description ...

}

...

type (namestring) {

... type description ...

}

input_voltage (namestring) {

... input voltage information ...

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}

output_voltage (namestring) {

... output voltage information ...

}

1.3 Reducing Library File Size

Large library files can compromise disk capacity and memory resources. To reduce file size

and improve file management, the syntax allows you to combine multiple source files by

referencing the files from within the source file containing the library group description.

Use the include_file statement to reference information in another file for inclusion

during library compilation. Be sure the directory of the included file is defined in your search

path—the include attribute takes only the file name as its value; a path is not allowed.

Syntax

include_file(file_nameid) ;

Example

cell( ) {

area : 0.1 ;

...

include_file(opc_file) ;

...

}

where opc_file contains the operating_conditions group statements.

Limitations

The include_file attribute has these requirements:

● Recursive include_file statements are not allowed; that is, the source files

that you include cannot also contain include_file statements.

● If the included file is not in the current directory, then the location of the included

file must be defined in your search path.

● Multiple file names are not allowed in an include_file statement. However,

there is no limit to the number of include_file statements you can have in

your main source file.

● An included file cannot substitute for a value statement. For example, the

following is not allowed:

cell ( ) {

area : 0.1 ;

...

pin_equal : include_file( source_fileid ) ;

}

● The include_file statement cannot substitute or cross the group boundary.

For example, the following is not allowed:

cell ( A ) include ( source_fileid )

where source_fileid is the following:

{

attribute : value ;

...

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}

1.4 library Group Name

The first line of the library group statement names the library. It is the first executable

line in your library.

1.4.1 Syntax

library (namestring) {

... library description ...

}

1.4.2 Example

A library called example1 looks like this:

library (example1) {

... library description ...

}

1.5 library Group Example

Example 1-3 shows a portion of a library group for a CMOS library. It contains buses and

uses a nonlinear timing delay model.

Example 1-3 CMOS library Group

library (example1) {

technology (cmos) ;

delay_model : table_lookup ;

date : "December 12, 2003" ;

revision : 2003.12 ;

bus_naming_style : "Bus%sPin%d" ;

...

}

1.6 Simple Attributes

Following are descriptions of the library group simple attributes. Similar sections

describing the default, complex, and group statement attributes complete this chapter.

1.6.1 bus_naming_style Simple Attribute

The bus_naming_style attribute defines the naming convention for buses in the library.

Syntax

bus_naming_style : "string";

string

Can contain alphanumeric characters, braces, underscores, dashes, or

parentheses. Must contain one %s symbol and one %d symbol. The %s and

%d symbols can appear in any order, but at least one nonnumeric

character must separate them.

The colon character is not allowed in a bus_naming_style attribute

value because the colon is used to denote a range of bus members.

You construct a complete bused-pin name by using the name of the

owning bus and the member number. The owning bus name is substituted

for the %s, and the member number replaces the %d.

If you do not define the bus_naming_style attribute,Liberty applies the default naming

convention, as shown in the following example.

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Example

bus_naming_style : "%s[%d]" ;

When the default naming convention is applied, member 1 of bus A becomes A[1].

The next example shows how you can use the bus_naming_style attribute to apply a

different naming convention.

Example

bus_naming_style : "Bus%sPin%d" ;

When this naming convention is applied, bus member 1 of bus A becomes BusAPin1, bus

member 2 becomes BusAPin2, and so on.

1.6.2 comment Simple Attribute

You use the comment attribute to include copyright or other product information in the

library report that you generate using the report_lib command. You can include only

one comment line in a library.

Syntax

comment : "string" ;

string

You can use an unlimited number of characters in the string, but all the

characters must be enclosed within quotation marks.

Example

The following comment line:

appears in the report like this:

1.6.3 current_unit Simple Attribute

The current_unit attribute specifies the unit for the drive current generated by output

pads. The pulling_current attribute for a pull-up or pull-down transistor also represents

its values in the specified unit.

Syntax

current_unit : valueenum ;

value

The valid values are 1uA, 10uA, 100uA, 1mA, 10mA, 100mA, and 1A. No

default value exists for the current_unit attribute if the attribute is

omitted.

Example

current_unit : 100uA ;

1.6.4 date Simple Attribute

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The optional date attribute identifies the date your library was created. The date appears

in the library report produced by the report_lib command.

Syntax

date : "date" ;

date

You can use any format within the quotation marks to report the date.

Example

date : "12 December 2003" ;

1.6.5 default_fpga_isd Simple Attribute

If you define more than one fpga_isd group, you must use the default_fpga_isd

attribute to specify which of those fpga_isd groups is the default.

Syntax

default_fpga_isd : fpga_isd_nameid ;

fpga_isd_name

The name of the default fpga_isd group.

Example

default_fpga_isd : lib_isd ;

1.6.6 default_threshold_voltage_group Simple Attribute

The default_threshold_voltage_group attribute specifies the name of a category to

which a cell belongs, based on the voltage characteristics of the cell.

Syntax

default_threshold_voltage_group : group_nameid ;

group_name

A string value representing the name of the category.

Example

default_threshold_voltage_group : "high_vt_cell" ;

1.6.7 delay_model Simple Attribute

Use the delay_model attribute to specify which delay model to use in the delay

calculations.

The delay_model attribute must be the first attribute in the library if a technology attribute

is not present. Otherwise, it should follow the technology attribute.

Syntax

delay_model : valueenum ;

value

Valid values are generic_cmos, table_lookup (nonlinear delay

model), piecewise_cmos, dcm (delay calculation module), and

polynomial (scalable polynomial delay model).

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Example

delay_model : table_lookup ;

1.6.8 em_temp_degradation_factor Simple Attribute

The em_temp_degradation_factor attribute specifies the electromigration exponential

degradation factor.

Syntax

em_temp_degradation_factor : valuefloat ;

value

A floating-point number in centigrade units consistent with other

temperature specifications throughout the library.

Example

em_temp_degradation_factor : 40.0 ;

1.6.9 fpga_domain_style Simple Attribute

Use the fpga_domain_style attribute to specify a value that you reference from a

calc_mode attribute in a domain group in a polynomial table.

Syntax

fpga_domain_style : "nameid" ;

name

The style value.

Example

fpga_domain_style : "speed";

1.6.10 fpga_technology Simple Attribute

Use this attribute to specify your FPGA technology. This attribute is required when your

library technology is FPGA.

Syntax

fpga_technology : "fpga_technology_namestring" ;

fpga_technology_name

The name of your FPGA technology.

Example

fpga_technology : "my_fpga_technology_1";

1.6.11 in_place_swap_mode Simple Attribute

In-place optimization occurs after placement and routing.

The in_place_swap_mode attribute specifies the criteria for cell swapping during in-place

optimization. The basic criteria for cell swapping are:

● The cells must have the same function.

● The cells must have the same number of pins, and the pins must have the same

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pin names.

Syntax

in_place_swap_mode : match_footprint | no_swapping ;

match_footprint

Cells are swapped if they meet the criteria and have the same footprint

attribute.

no_swapping

In-place optimization is disabled. The cell_footprint attribute is

ignored. The no_swapping value is the default for CMOS libraries.

Example

in_place_swap_mode : match_footprint ;

Use the report_lib command to print the type of in-place swap mode your technology

library is using.

1.6.12 input_threshold_pct_fall Simple Attribute

Use the input_threshold_pct_fall attribute to set the default value of the threshold

point on an input pin signal falling from 1 to 0. You can specify this attribute at the pin-level

to override the default value.

Syntax

input_threshold_pct_fall : trip_pointfloat ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the threshold

point of an input pin signal falling from 1 to 0. The default value is 50.0.

Example

input_threshold_pct_fall : 60.0 ;

1.6.13 input_threshold_pct_rise Simple Attribute

Use the input_threshold_pct_rise attribute to set the default value of the threshold

point on an input pin signal rising from 0 to 1. You can specify this attribute at the pin-level

to override the default value.

Syntax

input_threshold_pct_rise : trip_pointfloat ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the threshold

point of an input pin signal rising from 0 to 1. The default value is 50.0.

Example

input_threshold_pct_rise : 40.0 ;

1.6.14 leakage_power_unit Simple Attribute

The leakage_power_unit attribute is defined at the library level. It indicates the units of

the power values in the library. If this attribute is missing, the leakage-power values are

expressed without units.

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Syntax

leakage_power_unit : valueenum ;

value

Valid values are 1mW, 100uW (for 100mW), 10uW (for 10mW), 1uW (for

1mW), 100nW, 10nW, 1nW, 100pW, 10pW, and 1pW.

Example

leakage_power_unit : "100uW" ;

1.6.15 nom_calc_mode Simple Attribute

This optional attribute defines a default process point, one of the nominal operating

conditions for a library.

Syntax

nom_calc_mode : nameid ;

name

Represents the default process point.

Example

nom_calc_mode : nominal ;

1.6.16 nom_process Simple Attribute

The nom_process attribute defines process scaling, one of the nominal operating

conditions for a library.

Syntax

nom_process : valuefloat ;

value

A floating-point number that represents the degree of process scaling in

the cells of the library.

Example

nom_process : 1.0 ;

1.6.17 nom_temperature Simple Attribute

The nom_temperature attribute defines the temperature (in centigrade), one of the

nominal operating conditions for a library.

Syntax

nom_temperature : valuefloat ;

value

A floating-point number that represents the temperature of the cells in the

library.

Example

nom_temperature : 25.0 ;

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1.6.18 nom_voltage Simple Attribute

The nom_voltage attribute defines voltage, one of the nominal operating conditions for a

library.

Syntax

nom_voltage : valuefloat ;

value

A floating-point number that represents the voltage of the cells in the

library.

Example

nom_voltage : 5.0 ;

1.6.19 output_threshold_pct_fall Simple Attribute

Use the output_threshold_pct_fall attribute to set the value of the threshold point

on an output pin signal falling from 1 to 0.

Syntax

output_threshold_pct_fall : trip_pointfloat ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the threshold

point of an output pin signal falling from 1 to 0. The default value is 50.0.

Example

output_threshold_pct_fall : 40.0 ;

1.6.20 output_threshold_pct_rise Simple Attribute

Use the output_threshold_pct_rise attribute to set the value of the threshold point

on an output pin signal rising from 0 to 1.

Syntax

output_threshold_pct_rise : trip_pointfloat ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the threshold

point of an output pin signal rising from 0 to 1.The default value is 50.0.

Example

output_threshold_pct_rise : 40.0 ;

1.6.21 piece_type Simple Attribute

The piece_type attribute allows you the option of using capacitance to define the

piecewise linear model.

Syntax

piece_type : valueenum ;

value

Valid values are piece_length, piece_wire_cap, piece_pin_cap,

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and piece_total_cap.

Example

piece_type : piece_length ;

The piece_wire_cap, piece_pin_cap, and piece_total_cap values represent the

piecewise linear model extensions that cause modeling to use capacitance instead of

length. These values indicate wire capacitance alone, total pin capacitance, or the total wire

and pin capacitance. If the piece_type attribute is not defined, modeling defaults to the

piece_length model.

1.6.22 power_model Simple Attribute

The power_model attribute allows you to specify whether your library utilizes lookup tables

or scalable polynomial equations to model power.

Syntax

power_model : value ;

value

The valid values you can specify are table_lookup and polynomial. If no

value is specified, table_lookup is assumed.

Example

power_model : polynomial ;

1.6.23 preferred_output_pad_slew_rate_control Simple Attribute

Use the preferred_output_pad_slew_rate_control attribute to embed directly in

the library the desired preferred slew-rate control value.

Syntax

preferred_output_pad_slew_rate_control : valueenum ;

value

Valid values are high, medium, low, and none.

Example

preferred_output_pad_slew_rate_control : high ;

1.6.24 preferred_input_pad_voltage Simple Attribute

Use the preferred_input_pad_voltage and the

preferred_output_pad_voltage attributes to embed in the library the preferred

voltage values.

Syntax

preferred_input_pad_voltage : name1string; preferred_output_pad_voltage : name2string ;

name1

A string name for any of the input voltage groups defined in the library.

name2

A string name for any of the output voltage groups defined in the library.

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For more information about output and input voltage groups, see the “Defining Core Cells”

and “Defining I/O Pads” chapters in the Liberty User Guide, Volume 1.

1.6.25 preferred_output_pad_voltage Simple Attribute

For information about using the preferred_output_pad_voltage attribute, see the

descriotion of the “preferred_input_pad_voltage Simple Attribute” .

1.6.26 pulling_resistance_unit Simple Attribute

Use the pulling_resistance_unit attribute to define pulling resistance values for pull-

up and pull-down devices.

Syntax

pulling_resistance_unit : "unit" ;

unit

Valid unit values are 1ohm, 10ohm, 100ohm, and 1kohm. No default value

exists for pulling_resistance_unit if the attribute is omitted.

Example

pulling_resistance_unit : "10ohm" ;

1.6.27 revision Simple Attribute

The optional revision attribute defines a revision number for your library.

Syntax

revision : value ;

value

The value can be either a floating-point number or a string.

Example

revision : V3.1a ;

1.6.28 simulation Simple Attribute

Setting the simulation attribute to true lets a tool simulation library files.

Syntax

simulation : true | false ;

The default for the simulation attribute is true.

Example

simulation : true ;

1.6.29 slew_derate_from_library Simple Attribute

Use the slew_derate_from_library attribute to specify how the transition times need

to be derated to match the transition times between the characterization trip points.

Syntax

slew_derate_from_library : deratefloat ;

derate

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A floating-point number between 0.0 and 1.0. The default value is 1.0.

Example

slew_derate_from_library : 0.5;

1.6.30 slew_lower_threshold_pct_fall Simple Attribute

Use the slew_lower_threshold_pct_fall attribute to set the default value of the

lower threshold point used for modeling the delay of a pin falling from 1 to 0. You can

specify this attribute at the pin-level to override the default value.

Syntax

slew_lower_threshold_pct_fall : trip_pointvalue ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the lower

threshold point used for modeling the delay of a pin falling from 1 to 0. The

default value is 20.0.

Example

slew_lower_threshold_pct_fall : 30.0 ;

1.6.31 slew_lower_threshold_pct_rise Simple Attribute

Use the slew_lower_threshold_pct_rise attribute to set the default value of the

lower threshold point used in modeling the delay of a pin rising from 0 to 1. You can specify

this attribute at the pin-level to override the default value.

Syntax

slew_lower_threshold_pct_rise : trip_pointvalue ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the lower

threshold point used for modeling the delay of a pin rising from 0 to 1. The

default value is 20.0.

Example

slew_lower_threshold_pct_rise : 30.0 ;

1.6.32 slew_upper_threshold_pct_fall Simple Attribute

Use the slew_upper_threshold_pct_fall attribute to set the default value of the

upper threshold point used for modeling the delay of a pin falling from 1 to 0. You can

specify this attribute at the pin-level to override the default value.

Syntax

slew_upper_threshold_pct_fall : trip_pointvalue ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the upper

threshold point used to model the delay of a pin falling from 1 to 0. The

default value is 80.0.

Example

slew_upper_threshold_pct_fall : 70.0 ;

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1.6.33 slew_upper_threshold_pct_rise Simple Attribute

Use the slew_upper_threshold_pct_rise attribute to set the value of the upper

threshold point used for modeling the delay of a pin rising from 0 to 1. You can specify this

attribute at the pin-level to override the default value.

Syntax

slew_upper_threshold_pct_rise : trip_pointvalue ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the upper

threshold point used for modeling the delay of a pin rising from 0 to 1. The

default value is 80.0.

Example

slew_upper_threshold_pct_rise : 70.0 ;

1.6.34 time_unit Simple Attribute

Use attribute to identify the physical time unit used in the generated library.

Syntax

time_unit : unit ;

unit

Valid values are 1ps, 10ps, 100ps, and 1ns. The time_unit attribute

default value is 1ns.

Example

time_unit : 100ps ;

1.6.35 voltage_unit Simple Attribute

Use this attribute to scale the contents of the input_voltage and output_voltage

groups.

Additionally, the voltage attribute in the operating_conditions group represents

values in the voltage units.

Syntax

voltage_unit : unit ;

unit

Valid values are 1mV, 10mV, 100mV, and 1V. The default value is 1V.

Example

voltage_unit : 100mV;

1.7 Defining Default Attribute Values in a CMOS Technology Library

Within the library group of a CMOS technology library, you can define default values for

the pin and timing group attributes. Then, as needed, you can override the default

settings by defining corresponding attributes at the individual pin or timing group levels.

The following tables list the default attributes that you can define within the library

group and the attributes that override them.

● Table 1-1 lists the default attributes you can use in all the CMOS models.

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● Table 1-2 lists the default attributes you can use in Piecewise linear delay

models.

● Table 1-3 lists the default attributes you can use in CMOS linear delay models.

Table 1-1 CMOS Default Attributes for All Models

Default attribute Description Override with

default_cell_leakage_power Default leakage power

cell_leakage_power

default_connection_class Default connection

class connection_class

default_fanout_load Fanout load of input

pins fanout_load

default_inout_pin_cap Capacitance of inout

pins capacitance

default_input_pin_cap Capacitance of input

pins capacitance

default_intrinsic_fall Intrinsic fall delay of a

timing arc intrinsic_fall

default_intrinsic_rise Intrinsic rise delay of a

timing arc intrinsic_rise

default_leakage_power_density

Default leakage power

density cell_leakage_power

default_max_capacitance Maximum capacitance

of output pins max_capacitance

default_max_fanout Maximum fanout of all

output pins max_fanout

default_max_transition Maximum transition of

output pins max_transition

default_max_utilization Maximum limit of

utilization No override available

default_min_porosity Minimum porosity

constraint set_min_porosity

default_operating_conditions Default operating

conditions for the

library

operating_conditions

default_output_pin_cap Capacitance of output

pins capacitance

default_slope_fall Fall sensitivity factor

of a timing arc slope_fall

default_slope_rise Rise sensitivity factor

of a timing arc slope_rise

default_wire_load Wire load No override available

default_wire_load_area Wire load area No override available

default_wire_load_capacitance

Wire load capacitance

No override available

default_wire_load_mode Wire load mode set_wire_load -mode

default_wire_load_resistance Wire load resistance No override available

default_wire_load_selection Wire load selection No override available

Table 1-2 CMOS Default Attributes for Piecewise Linear Delay Models

Default attribute Description Override with

default_fall_delay_intercept

Falling-edge intercept

of a timing arc fall_delay_intercept

default_fall_pin_resistance Fall resistance of

output pins fall_pin_resistance

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default_rise_delay_intercept

Rising-edge intercept

of a timing arc rise_delay_intercept

default_rise_pin_resistance Rise resistance of

output pins rise_pin_resistance

Table 1-3 CMOS Default Attributes for Linear Delay Models

Default attribute Description Override with

default_inout_pin_fall_res Fall resistance of inout pins fall_resistance

default_inout_pin_rise_res Rise resistance of inout pins rise_resistance

default_output_pin_fall_res

Fall resistance of output pins fall_resistance

default_output_pin_rise_res

Rise resistance of output pins

rise_resistance

1.8 Complex Attributes

Following are the descriptions of the technology library complex attributes.

1.8.1 capacitive_load_unit Complex Attribute

The capacitive_load_unit attribute specifies the unit for all capacitance values within

the technology library, including default capacitances, max fanout capacitances, pin

capacitances, and wire capacitances.

Syntax

capacitive_load_unit (valuefloat,unitenum) ;

value

A floating-point number.

unit

Valid values are ff and pf.

The first line in the following example sets the capacitive load unit to 1 pf.

The second line represents capacitance in terms of the standard unit load

of an inverter.

Example

capacitive_load_unit (1,pf) ;

capacitive_load_unit (0.059,pf) ;

The capacitive_load_unit attribute has no default value when the attribute is omitted.

1.8.2 default_part Complex Attribute

The default_part attribute specifies the default part and the speed used for an FPGA

design.

Syntax

default_part (default_part_namestring, speed_gradestring) ;

default_part_name

The name of the default part.

speed_grade

The speed grade the design uses.

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Example

default_part ("AUTO", "-5") ;

1.8.3 define Complex Attribute

Use this special attribute to define new, temporary, or user-defined attributes for use in

symbol and technology libraries.

Syntax

define ("attribute_name", "group_name", "attribute_type") ;

attribute_name

The name of the attribute you are creating.

group_name

The name of the group statement in which the attribute is to be used.

attribute_type

The type of the attribute that you are creating; valid values are Boolean,

string, integer, or float.

The following example shows how to define a new string attribute called bork, which is

valid in a pin group:

Example

define ("bork", "pin", "string") ;

You give the new library attribute a value by using the simple attribute syntax:

bork : "nimo" ;

1.8.4 define_cell_area Complex Attribute

The define_cell_area attribute defines the area resources a cell uses, such as the

number of pad slots.

Syntax

define_cell_area (area_name, resource_type) ;

area_name

A name of a resource type. You can associate more than one area_name

with each of the predefined resource types.

resource_type

The resource type can be

❍ pad_slots

❍ pad_input_driver_sites

❍ pad_output_driver_sites

❍ pad_driver_sites

Use the pad_driver_sites type when you do not need to discriminate between

input and output pad driver sites.

You can define as many cell area types as you need, as shown here.

Example

define_cell_area (bond_pads, pad_slots) ;

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define_cell_area (pad_drivers, pad_driver_sites) ;

After you define the cell area types, specify the resource type in a cell group to identify

how many of each resource type the cell requires, as shown here.

Example

cell(IV_PAD) {

bond_pads : 1 ;

...

}

1.8.5 define_group Complex Attribute

Use this special attribute to define new, temporary, or user-defined groups for use in

technology libraries.

Syntax

define_group (groupid, parent_nameid) ;

group

The name of the user-defined group.

parent_name

The name of the group statement in which the attribute is to be used.

The following example shows how you define a new group called myGroup:

Example

define_group (myGroup, timing ) ;

1.8.6 library_features Complex Attribute

The library_features attribute lets other other tools use the command features that

you specify as attribute values.

Syntax

library_features (valueid ) ;

value

Valid values are report_delay_calculation,

report_noise_calculation, report_user_data and

allow_update_attribute. The default value is none.

report_delay_calculation

Displays timing information.

report_noise_calculation

Displays noise information for tied-off cells.

report_user_data

Allows the report_lib command to display information about user-

defined attributes and groups.

allow_update_attribute

Allows the update_lib and set_lib_attribute commands to

overwrite user-defined attribute values.

Example

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library_features (report_delay_calculation) ;

1.8.7 piece_define Complex Attribute

The piece_define complex attribute statement defines the pieces used in the piecewise

linear delay model. With this attribute, you can define the ranges of length or capacitance

for indexed variables, such as rise_pin_resistance, used in the delay equations.

Syntax

piece_define ("range0 [range1 range2 ...]") ;

Each range is a floating-point number defining the lower limit of the respective range. If the

piecewise linear model is in the piece_length mode, as described in the piece_type

attribute section, a wire whose length is between range0 and range1 is named as piece 0, a

wire whose length is between range1 and range2 is piece 1, and so on.

For example, in the following piece_define specification, a wire of length 5 is referred to

as piece 0, a wire of length 12 is piece 1, and a wire of length 20 or more is piece 2.

Example

piece_define ("0 10 20") ;

Each capacitance is a positive floating-point number defining the lower limit of the

respective range. A piece of wire whose capacitance is between range0 and range1 is

identified as piece0 , a capacitance between range1 and range2 is piece 1, and so on.

You must include in the piece_define statement all ranges of wire length or capacitance

for which you want to enter a unique attribute value.

1.8.8 routing_layers Complex Attribute

The routing_layers attribute declares the routing layers available for place and route

for the library. The routing_layers attribute is a string that represents the symbolic

name used later in a library to describe routability information associated with each layer.

The routing_layers attribute must be defined in the library before other routability

information in a cell. Otherwise, cell routability information in the library is considered an

error. Each different library can have only one routing_layers complex attribute.

Syntax

routing_layers("routing_layer_1_name",...,

"routing_layer_n_name") ;

The report_lib command displays library routing layer information. The report looks

similar to the following example.

Porosity information:

Routing_layers:

"metal2" "metal3"

default_min_porosity: 15.0

If there is no porosity information in the library, report_lib displays the following line:

No porosity information specified.

1.8.9 technology Complex Attribute

Use this attribute to specify which technology family is used in the library. When you define

the technology attribute, it must be the first attribute you use and it must be placed at the

top of the listing (see Example 1-2).

Syntax

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technology (nameenum) ;

name

Valid values are CMOS or FPGA. If you specify FPGA, you must also

specify the fpga_technology attribute at the library level. The default is

CMOS.

Example

technology (cmos) ;

1.8.10 voltage_map Complex Attribute

Use this attribute to specifyhe cell-level pg_pin groups.

Syntax

voltage_map (voltage_nameid, voltage_valuefloat) ;

voltage_name

Specifies a power supply.

voltage_value

Specifies a voltage value.

Example

voltage_map (VDD1, 3.0) ;

1.9 Group Statements

Following are the descriptions of the technology library group statement attribute.

1.9.1 base_curves Group

The base_curves group is a library-level group that contains the detailed description of

normalized base curves.

Syntax

library(my_compact_ccs_lib) {

…

base_curves (base_curves_name) {

…

}

Example

library(my_lib) {

…

base_curves (ctbct1) {

…

}

Complex Attributes

base_curve_type

curve_x

curve_y

1.9.2 base_curve_type Complex Attribute

The base_curve_type attribute specifies the type of base curve. Currently, the only valid

value for base_curve_type is ccs_timing_half_curve.

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Syntax

base_curve_type: enum (ccs_timing_half_curve) ;

Example

base_curve_type : ccs_timing_half_curve ;

1.9.3 curve_x Complex Attribute

Each base curve consists of one curve_x and one curve_y. The curve_x attribute

should be defined before curve_y for better readability and easier implementation. Only

one curve_x attribute can be specified for each base_curves group. The data array is

the x-axis value of the normalized base curve. The curve_x value must be between 0 and

1 and increase monotonically for ccs_timing_half_curve type base curves.

Syntax

curve_x ("float…, float") ;

Example

curve_x ("0.2, 0.5, 0.8") ;

1.9.4 curve_y Complex Attribute

Each base curve consists of one curve_x and one curve_y. The curve_x attribute

should be defined before curve_y for better readability and easier implementation.

The curve_y attribute includes the following:

● The curve_id value, which specifies the base curve identifier.

● The data array, which is the Y-axis value of the normalized base curve.

Syntax

curve_y (curve_id, "float…, float") ;

Example

curve_y (1, "0.8, 0.5, 0.2");

1.9.5 compact_lut_template Group

The compact_lut_template group is a lookup table template used for compact CCS

timing modeling.

Syntax

library (my_compact_ccs_lib) {

...

compact_lut_template (template_name) {

...

}

Example

library (my_lib) {

...

compact_lut_template (LTT3) {

...

}

Simple Attributes

base_curves_group

variable_1

variable_2

variable_3

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Complex Attributes

index_1

index_2

index_3

1.9.6 base_curves_group Simple Attribute

The base_curves_group attribute is required in the compressed_lut_template

group. Its value is the specified base_curves group name. The type of base curve in the

base_curves group determines the index_3 values when the

compact_lut_template is used.

Syntax

base_curves_group : base_curves_name ;

Example

base_curves_group : ctbc1 ;

1.9.7 variable_1 and variable_2 Simple Attributes

The only valid values for the variable_1 and variable_2 attributes are

input_net_transition and total_output_net_capacitance.

Syntax

variable_1 : input_net_transition | total_output_net_capacitance;

variable_2 : input_net_transition | total_output_net_capacitance;

Example

variable_1 : input_net_transition ;

variable_2 : total_output_net_capacitance ;

1.9.8 variable_3 Simple Attribute

The only legal string value for the variable_3 attribute is curve_parameters.

Syntax

variable_3 : curve_parameters ;

Example

variable_3 : curve_parameters ;

1.9.9 index_1 and index_2 Complex Attributes

The index_1 and index_2 attributes are required. The index_1 and index_2 attributes

define the input_net_transition and total_output_net_capacitance values.

The index value for input_net_transition or total_output_net_capacitance is

a floating-point number.

Syntax

index_1 ("float..., float") ;

index_2 ("float..., float") ;

Example

index_1 ("0.1, 0.2") ;

index_2 ("1.0, 2.0") ;

1.9.10 index_3 Complex Attribute

The string values in index_3 are determined by the base_curve_type value in the

base_curve group. When ccs_timing_half_curve is the base_curve_type value,

the following six string values (parameters) should be defined: init_current,

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peak_current, peak_voltage, peak_time, left_id, right_id; their order is not

fixed.

More than six parameters are allowed if a more robust syntax is required or for

circumstances where more parameters are needed in order to describe the original data.

Syntax

index_3 ("string..., string") ;

Example

index_3 ("init_current, peak_current, peak_voltage,

peak_time, left_id, right_id") ;

1.9.11 dc_current_template Group

The dc_current_template group defines a template for specifying a two-dimentional

dc_current table or a three-dimensional vector table.

Syntax

library (namestring) {

dc_current_template (template_nameid) {

... template description ...

}

Simple Attributes

variable_1

variable_2

variable_3

Complex Attributes

index_1

index_2

index_3

variable_1, variable_2, and variable_3 Simple Attributes

For a two-dimensional dc_current table, the value you can assign to variable_1 is

input_voltage, and the value you can assign to variable_2 is output_voltage.

For a three-dimensional vector table, the value you can assign to variable_1 is

input_net_transition, and the value you can assign to variable_2 is

output_net_transition. The value you can assign to variable_3 is time.

index_1, index_2, and index_3 Complex Attributes

Along with variable_1, variable_2, and variable_3, you must specify the index values.

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

index_3 ("float, ..., float") ;

Example

library (my_library) {

...

dc_current_template (my_template) {

variable_1 : input_net_transition ;

variable_2 : output_net_transition ;

variable_3 : time ;

index_1 ("0.0, 0.0") ;

index_2 ("0.0, 0.0") ;

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index_3 ("0.0, 0.0") ;

}

...

}

1.9.12 em_lut_template Group

The em_lut_template group is defined at the library group level.

Syntax

library (namestring) {

em_lut_template(namestring) {

variable_1 : input_transition_time | total_output_net_capacitance ;

variable_2 : input_transition_time | total_output_net_capacitance ;

index_1 : ("float, ..., float");

index_2 : ("float, ..., float");

}

The em_lut_template group creates a template of the index used by the

electromigration group defined in the pin group level.

variable_1, variable_2, and variable_3 Simple Attributes

Following are the values that you can assign to the templates for electromigration tables.

Use variable_1 to assign values to one-dimensional tables; use variable_2 to assign

values for two-dimensional tables; and use variable_3 to assign values for three-

dimensional tables:

variable_1 : input_transition_time | total_output_net_capacitance ;

variable_2 : input_transition_time | total_output_net_capacitance ;

The value you assign to variable_1 is determined by how the index_1 complex

attribute is measured, and the value you assign to variable_2 is determined by how the

index_2 complex attribute is measured.

Assign input_transition_time to variable_1 if the complex attribute index_1 is

measured with the input net transition time of the pin specified in the related_pin

attribute or the pin associated with the electromigration group. Assign

total_output_net_capacitance to variable_1 if the complex attribute index_1 is

measured with the loading of the output net capacitance of the pin associated with the

em_max_toggle_rate group.

Assign input_transition_time to variable_2 if the complex attribute index_2 is

measured with the input net transition time of the pin specified in the related_pin or the

related_bus_pins attribute or the pin associated with the electromigration group.

Assign total_output_net_capacitance to variable_2 if the complex attribute

index_2 is measured with the loading of the output net capacitance of the pin associated

with the electromigration group.

index_1 and index_2 Complex Attributes

You can use these optional attributes to specify the first and second dimension breakpoints

used to characterize cells for electromigration within the library.

Syntax

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

float

For index_1, the floating-point numbers that specify the breakpoints of

the first dimension of the electromigration table used to characterize cells

for electromigration within the library. For index_2, the floating-point

numbers that specify the breakpoints for the second dimension of the

electromigration table used to characterize cells for electromigration within

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the library.

You can overwrite the values entered for the em_lut_template group’s index_1 by

entering values for the em_max_toggle_rate group’s index_1. You can overwrite the

values entered for the em_lut_template group’s index_2 by entering values for the

em_max_toggle_rate group’s index_2.

The following are the rules for the relationship between variables and indexes:

● If you have variable_1, you can have only index_1.

● If you have variable_1 and variable_2, you can have index_1 and

index_2.

● The value you enter for variable_1 (used for one-dimensional tables) is

determined by how index_1 is measured. The value you enter for

variable_2 (used for two-dimensional tables) is determined by how index_2

is measured.

Examples

em_lut_template (output_by_cap_and_trans) {

variable_1 : total_output_net_capacitance ;

variable_2 : input_transition_time ;

index_1 ("0.0, 5.0, 20.0") ;

index_2 ("0.0, 1.0, 2.0") ;

}

em_lut_template (input_by_trans) {

variable_1 : input_transition_time;

index_1 ("0.0, 1.0, 2.0");

}

1.9.13 fall_net_delay Group

The fall_net_delay group is defined at the library level, as shown here:

library (name) {

fall_net_delay (name){

... fall net delay description ...

}

Complex Attributes

index_1 ("float,...,float") ;

index_2 ("float,...,float") ;

values ("float,...,float","float,...,float");

The rise_net_delay and the fall_net_delay groups define, in the form of lookup

tables, the values for rise and fall net delays. This indexing allows the library developer to

model net delays as any function of output_transition and rc_product.

The net delay tables in one library have no effect on computations related to cells from

other libraries.

To overwrite the lookup table default index values, specify the new index values before the

net delay values, as shown in the following examples.

Example 1-4 shows an example of the fall_net_delay group.

Example 1-4 fall_net_delay Group

fall_net_delay (net_delay_table_template) {

index_1 ("0, 1, 2") ;

index_2 ("1, 0, 2") ;

values ("0.00, 0.57", "0.10, 0.48") ;

}

1.9.14 fall_transition_degradation Group

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The fall_transition_degradation group is defined at the library level, as shown

here:

library (name) {

fall_transition_degradation(name) {

... fall transition degradation description ...

}

Complex Attributes

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

values ("float, ..., float", "float, ...,float") ;

The fall_transition_degradation group and the

rise_transition_degradation group describe, in the form of lookup tables, the

transition degradation functions for rise and fall transitions. The lookup tables are indexed

by the transition time at the net driver and the connect delay between the driver and a

particular load. This indexing allows the library developer to model degraded transitions as

any function of output-pin transition and connect delay between the driver and the load.

Transition degradation tables are used for indexing into any delay table in a library that has

the input_net_transition, constrained_pin_transition, or

related_pin_transition table parameters in the lu_table_template group.

The transition degradation tables in one library have no effect on computations related to

cells from other libraries. Example 1-5 shows a fall_transition_degradation group.

Example 1-5 fall_transition_degradation Group

fall_transition_degradation(trans_deg) {

index_1 ("1, 0, 2") ;

index_2 ("0, 1, 2") ;

values ("0.0, 0.8", "1.0, 1.8") ;

}

1.9.15 faults_lut_template

To model yield information, use the faults_lut_template group to specify fab names

and time ranges applicable for all fault tables in the .lib file. You define fault tables in the

cell-level functional_yield_metric group using the average_number_of_faults

attribute. See “functional_yield_metric Group” . Define the faults_lut_template group

at the library level, as shown here:

Syntax

library (namestring) {

...

faults_lut_template(namestring) {

variable_1 : valueenum ;

variable_2 : valueenum ;

index_1 ("float, ..., float");

index_2 ("float, ..., float");

}

Simple Attributes

variable_1

variable_2

Complex Attributes

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index_1

index_2

The following are the values you can assign to the variables:

faults_lut_template(namestring) {

variable_1 : fab_name;

variable_2 : time_range;

}

Example

library ( my_library_name ) {

…

faults_lut_template ( my_faults_temp ) {

variable_1 : fab_name;

variable_2 : time_range;

index_1 ( " fab1, fab2, fab3 ");

index_2 (" 2005.01, 2005.07, 2006.01, 2006.07 ");

}

…

cell ( and2 ) {

…

functional_yield_metric () {

average_number_of_faults ( my_faults_temp ) {

values ( " 73.5, 78.8, 85.0, 92 ",\

" 74.3, 78.7, 84.8, 92.2 ",\

" 72.2, 78.1, 84.3, 91.0 " );

}

…

} /* end of cell */

} /* end of library */

This template example represents fault data for three fab lines (fab1, fab2, fab3) and holds

fault data collected for four time ranges:

● 2005.01 represents a time range from January 2005 to June 2005

● 2005.07 represents a time range from July 2005 to December 2005

● 2006.01 represents a time range from January 2006 to June 2006

● 2006.07 represents July 2006 or later

For details on the functional_yield_metric group, see “functional_yield_metric

Group” .

1.9.16 input_voltage Group

An input_voltage group is defined in the library group to designate a set of input

voltage ranges for your cells.

Syntax

library (namestring) {

input_voltage (namestring) {

vil : float | expression ;

vih : float | expression ;

vimin : float | expression ;

vimax : float | expression ;

}

vil

The maximum input voltage for which the input to the core is guaranteed to

be a logic 0.

vih

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The minimum input voltage for which the input to the core is guaranteed to

be a logic 1.

vimin

The minimum acceptable input voltage.

vimax

The maximum acceptable input voltage.

After you define an input_voltage group, you can use its name with the

input_voltage simple attribute in a pin group of a cell. For example, you can define an

input_voltage group with a set of high and low thresholds and minimum and maximum

voltage levels and use the pin group to assign those ranges to the cell pin, as shown here.

Example

pin() {

...

input_voltage : my_input_voltages ;

...

}

The value of each attribute is expressed as a floating-point number, an expression, or both.

Table 1-4 lists the predefined variables that can be used in an expression.

Table 1-4 Voltage-Level Variables for the input_voltage Group

CMOS/BiCMOS variable Default value

VDD 5V

VSS 0V

VCC 5V

The default values represent nominal operating conditions. These values fluctuate with the

voltage range defined in the operating_conditions group.

All voltage values are in the units you define with the library group voltage_unit

attribute.

Example 1-6 shows a collection of input_voltage groups.

Example 1-6 input_voltage Groups

input_voltage(CMOS) {

vil : 0.3 * VDD ;

vih : 0.7 * VDD ;

vimin : -0.5 ;

vimax : VDD + 0.5 ;

}

input_voltage(TTL_5V) {

vil : 0.8 ;

vih : 2.0 ;

vimin : -0.5 ;

vimax : VDD + 0.5 ;

}

1.9.17 fpga_isd Group

You can define one or more fpga_isd groups at the library-level to specify the drive

current, IO voltages, and slew rates for fpga parts and cells.

Note:

When you specify more than one fpga_isd group, you must also define the library-level

default_fpga_isd attribute to specify which fpga_isd group touse as the default.

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Syntax

library (namestring) {

fpga_isd (fpga_isd_namestring ) {

... description ...

}

Example

fpga_isd (part_cell_isd) {

... description ...

}

Simple Attributes

drive

io_type

slew

drive Simple Attribute

The drive attribute is optional and specifies the output current of the FPGA part or the

FPGA cell.

Syntax

drive : valueid

value

A string

Example

drive : 24 ;

io_type Simple Attribute

The io_type attribute is required and specifies the input or output voltage of the FPGA

part or the FPGA cell.

Syntax

io_type : valueid

value

A string

Example

io_type : LVTTL ;

slew Simple Attribute

The slew attribute is optional and specifies whether the slew of the FPGA part or the

FPGA cell is FAST or SLOW.

Syntax

slew : valueid

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value

Valid values are FAST and SLOW.

Example

slew : FAST ;

1.9.18 iv_lut_template Group

The iv_lut_template group describes a template for specifying a current-voltage curve.

The template specifies I-V output voltage of the breakpoints.

Syntax

library (namestring) {

iv_lut_template (template_namestring ) {

... template description ...

}

Simple Attribute

variable_1

Complex Attribute

index_1

variable_1 Simple Attribute

You can assign the following value to the template for one-dimensional current-voltage

tables.

variable_1 : iv_output_voltage ;

index_1 Complex Attribute

index_1 ("float, ..., float");

Example

library (my_library) {

...

iv_lut_template (my_template) {

variable_1 : iv_output_voltage ;

index_1 ("-1, -0.1, 0.8, 1.6, 2") ;

}

...

}

1.9.19 lu_table_template Group

Use the lu_table_template group to define templates of common information to use in

lookup tables. Define the lu_table_template group at the library level, as shown here:

Syntax

library (namestring) {

...

lu_table_template(namestring) {

variable_1 : valueenum ;

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variable_2 : valueenum ;

variable_3 : valueenum ;

index_1 ("float, ..., float");

index_2 ("float, ..., float");

index_3 ("float, ..., float");

domain(domain_1_namestring) {

...

}

Simple Attributes

variable_1

variable_2

variable_3

Complex Attributes

index_1

index_2

index_3

Group

domain

normalized_voltage Variable

The normalized_voltage variable is specified under the lu_table_template table in

order to describe a collection of waveforms under various input slew values. For a given

input slew in index_1 (for example, index_1[0] = 1.0 ns), the index_2 values are a set of

points that represent how the voltage rises from 0 to VDD in a rise arc, or from VDD to 0 in

a fall arc.

Note:

The normalized_voltage variable can be used only with driver waveform syntax. For

more information, see the “Driver Waveform Support” section in the “Timing Arcs” chapter

in the Liberty User Guide, Volume 1.

Syntax

lu_table_template (waveform_template) {

variable_1 : input_net_transition;

variable_2 : normalized_voltage;

index_1 ("0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7");

index_2 ("0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9");

}

Rise Arc Example

normalized_driver_waveform (waveform_template) {

index_1 ("1.0"); /* Specifies the input net transition*/

index_2 ("0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0"); /* Specifies the voltage normalized

to VDD */

values ("0, 0.2, 0.4, 0.6, 0.8, 0.9, 1.1"); /* Specifies the time when the

voltage reaches the index_2 values*/

}

The lu_table_template table represents an input slew of 1.0 ns, when the voltage is

0%, 10%, 30%, 50%, 70%, 90% or 100% of VDD, and the time values are 0, 0.2, 0.4, 0.6,

0.8, 0.9, 1.1 (ns). Note that the time value can go beyond the corresponding input slew

because a long tail might exist in the waveform before it reaches the final status.

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variable_1, variable_2, variable_3, and variable_4 Simple Attributes

In Composite Current Source (CCS) Noise Tables:

Use lookup tables to create the lookup-table templates for the groups within the

ccsn_first_stage and ccsn_last_stage groups: the dc_current group and

vectors of the output_voltage_rise group, output_voltage_fall group,

propagated_noise_low group, and propagated_noise_high group.

You can assign the following values to the variables to specify the template used for the

dc_current tables:

lu_table_template(<dc_template_name>) {

variable_1 : input_voltage;

variable_2 : output_voltage;

}

You can assign the following values to the variables to specify the template used for the

vectors of the output_current_rise group and output_current_fall group.

lu_table_template(<output_voltage_template_name>) {

variable_1 : input_net_transition;

variable_2 : total_output_net_capacitance;

variable_3 : time;

}

You can assign the following values to the variables to specify the template used for the

vector's of the propagated_noise_low and propagated_noise_high group.

lu_table_template(<propagated_noise_template_name>) {

variable_1 : input_noise_height;

variable_2 : input_noise_width;

variable_3 : total_output_net_capacitance;

variable_4 : time;

In Timing Delay Tables:

Following are the values that you can assign for variable_1, variable_2, and

variable_3 to the templates for timing delay tables:

input_net_transition | total_output_net_capacitance |

output_net_length | output_net_wire_cap |

output_net_pin_cap |

related_out_total_output_net_capacitance |

related_out_output_net_length |

related_out_output_net_wire_cap |

related_out_output_net_pin_cap ;

The values that you can assign to the variables of a table specifying timing delay depend

on whether the table is one-, two-, or three-dimensional.

In Constraint Tables:

Following are the values (divided into sets) that you can assign for variable_1,

variable_2, and variable_3 to the templates for constraint tables:

constrained_pin_transition | related_pin_transition |

related_out_total_output_net_capacitance |

related_out_output_net_length |

related_out_output_net_wire_cap |

related_out_output_net_pin_cap ;

In Wire Delay Tables:

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The following is the value set that you can assign for variable_1, variable_2, and

variable_3 to the templates for wire delay tables:

fanout_number | fanout_pin_capacitance | driver_slew ;

The values that you can assign to the variables of a table specifying wire delay depends on

whether the table is one-, two-, or three-dimensional.

In Net Delay Tables:

The following is the value set that you can assign for variable_1 and variable_2 to the

templates for net delay tables:

output_transition | rc_product ;

The values that you can assign to the variables of a table specifying net delay depend on

whether the table is one- or two-dimensional.

In Degradation Tables:

The following values apply only to templates for transition time degradation tables:

variable_1 : output_pin_transition | connect_delay ;

variable_2 : output_pin_transition | connect_delay ;

The cell degradation table template allows only one-dimensional tables:

variable_1 : input_net_transition

Following are the rules for the relationship between variables and indexes:

● If you have variable_1, you must have index_1.

● If you have variable_1 and variable_2, you must have index_1 and

index_2.

● If you have variable_1, variable_2, and variable_3, you must have

index_1, index_2, and index_3.

CMOS Nonlinear Timing Model Examples

lu_table_template (constraint) {

variable_1 : related_pin_transition ;

variable_2 : related_out_total_output_net_capacitance ;

variable_3 : constrained_pin_transition ;

index_1 ("1.0, 1.5, 2.0") ;

index_2 ("1.5, 1.0, 2.0") ;

index_3 ("1.0, 2.0, 1.5") ;

}

lu_table_template (basic_template) {

variable_1 : input_net_transition;

variable_2 : total_output_net_capacitance;

index_1 ("0.0, 0.5, 1.5, 2.0");

index_2 ("0.0, 2.0, 4.0, 6.0");

}

Syntax

calc_mode : namestring ;

name

The name of the associated process mode.

domain Group

In the case of a piecewise lookup table, use one or more domain groups in the

lu_table_template group to specify subsets of the lookup table template. Variables in a

domain group can be the variables in the lu_table_template group.

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Syntax

library (namestring) {

lu_table_template (template_namestring) {

domain(domain_1_nameid) {

... domain description ...

}

domain_1_name

A string representing the name of the domain.

Simple Attributes

calc_mode

variable_1

variable_2

variable_3

Complex Attributes

index_1

index_2

index_3

calc_mode Simple Attribute

An optional attribute, you can use calc_mode to specify an associated process mode.

Example

calc_mode : OC1 ;

variable_1, variable_2, and variable_3 Simple Attributes

The variables in a domain group are a subset of the variables in the

lu_table_template group.

1.9.20 maxcap_lut_template Group

The maxcap_lut_template group defines a template for specifying the maximum

acceptable capacitance of an input or an output pin.

Syntax

library (namestring) {

maxcap_lut_template (template_nameid) {

... template description ...

}

Simple Attributes

variable_1

variable_2

Complex Attributes

index_1

index_2

variable_1 and variable_2 Simple Attributes

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The value you can assign to variable_1 is frequency. The value you can assign to

variable_2 is input_transition_time.

index_1 and index_2 Complex Attributes

Along with variable_1 and variable_2, you must specify the index values.

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

Example

library (my_library) {

...

maxcap_lut_template (my_template) {

variable_1 : frequency ;

variable_2 : input_transition_time ;

index_1 ("100.0000, 200.0000") ;

index_2 ("0.0, 0.0") ;

}

...

}

1.9.21 maxtrans_lut_template Group

The maxtrans_lut_template group defines a template for specifying the maximum

acceptable transition time of an input or an output pin.

Syntax

library (namestring) {

maxtrans_lut_template (template_nameid) {

... template description ...

}

Simple Attributes

variable_1

variable_2

variable_3

Complex Attributes

index_1

index_2

index_3

variable_1, variable_2, and variable_3 Simple Attributes

The value you can assign to variable_1 is frequency. The value you can assign to

variable_2 is input_transition_time. The value you can assign to variable_3 is

total_output_net_capacitance.

index_1, index_2, and index_3 Complex Attributes

Along with variable_1, variable_2, and variable_3, you must specify the index values.

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

index_3 ("float, ..., float") ;

Example

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library (my_library) {

...

maxtrans_lut_template (my_template) {

variable_1 : frequency ;

variable_2 : input_transition_time ;

variable_3 : total_output_net_capacitance ;

index_1 ("100.0000, 200.0000") ;

index_2 ("0.0, 0.0") ;

index_3 ("0.0, 0.0") ;

}

...

}

1.9.22 noise_lut_template Group

The noise_lut_template group defines a template for specifying a noise immunity

curve. Use the template to specify the input noise width output load and breakpoints that

represent the input height table.

Syntax

library (namestring) {

noise_lut_template (template_nameid) {

... template description ...

}

Simple Attributes

variable_1

variable_2

Complex Attributes

index_1

index_2

variable_1 and variable_2 Simple Attributes

The values you can assign to variable_1 and variable_2 are input_noise_width and

total_output_net_capacitance.

index_1 and index_2 Complex Attributes

Along with variable_1 and variable_2, you must define both index_1 and index_2.

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

Example

library (my_library) {

...

noise_lut_template (my_template) {

variable_1 : input_noise_width ;

variable_2 : total_output_capacitance ;

index_1 ("0, 0.1, 2") ;

index_2 ("0, 2") ;

}

...

}

1.9.23 normalized_driver_waveform Group

The library-level normalized_driver_waveform group represents a collection of driver

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waveforms under various input slew values. The index_1 specifies the input slew and

index_2 specifies the normalized voltage.Note that the slew index in the

normalized_driver_waveform table is based on the slew derate and slew trip points of

the library (global values). When applied on a pin or cell with different slew or slew derate,

the new slew should be interpreted from the waveform.

Simple Attributes

driver_waveform_name

Complex Attributes

index_1

index_2

values

Syntax

normalized_driver_waveform(waveform_template_name) {

driver_waveform_name : string; /* Specifies the name of

the driver waveform table */

index_1 ("float…, float"); /* Specifies input net

transition */

index_2 ("float…, float"); /* Specifies normalized

voltage */

values ( "float…, float", \ /* Specifies the time in

library units */

…, \

"float…, float");

}

Example

normalized_driver_waveform (waveform_template) {

index_1 ("1.0"); /* Specifies the input net transition*/

index_2 ("0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0"); /* Specifies the voltage normalized

to VDD */

values ("0, 0.2, 0.4, 0.6, 0.8, 0.9, 1.1"); /* Specifies the time when the

voltage reaches the index_2 values*/

}

driver_waveform_name Simple Attribute

The driver_waveform_name string attribute differentiates the driver waveform table from

other driver waveform tables when multiple tables are defined. Cell-specific and rise- and

fall-specific driver waveform usage modeling depend on this attribute.

The driver_waveform_name attribute is optional. You can define a driver waveform

table without the attribute, but there can be only one table in a library, and that table is

regarded as the default driver waveform table for all cells in the library. If more than one

table is defined without the attribute, the last table is used. The other tables are ignored and

not stored in the .db file.

Syntax

driver_waveform_name : string ;

Example

normalized_driver_waveform (waveform_template) {

driver_waveform_name : clock_driver ;

index_1 ("0.15, 0.25, 0.35, 0.45, 0.55, 0.65, 0.75");

index_2 ("0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9");

values ("0.012, 0.03, 0.045, 0.06, 0.075, 0.090, 0.105,

0.13, 0.145", \

… … …

"0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9");

1.9.24 operating_conditions Group

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Use this group to define operating conditions; that is, process, voltage, and temperature.

You define an operating_conditions group at the library-level, as shown here:

Syntax

library (namestring) {

operating_conditions (namestring) {

... operating conditions description ...

}

Simple Attributes

calc_mode : nameid ;

parameteri : float ;

process : float ;

temperature : float ;

tree_type : valueenum;

voltage : float ;

Complex Attribute

power_rail (string, float) ; /* one or more */

calc_mode Simple Attribute

An optional attribute, you can use calc_mode to specify an associated process mode.

Syntax

calc_mode : nameid ;

name

The name of the associated process mode.

parameter i Simple Attribute

Use this optional attribute to specify values for up to five user-defined variables.

Syntax

parameteri : valuefloat ; /* i = 1..5 */

value

A floating-point number representing the variable value.

process Simple Attribute

Use the process attribute to specify a scaling factor to account for variations in the

outcome of the actual semiconductor manufacturing steps.

Syntax

process : valuefloat ;

value

A floating-point number from 0 through 100.

temperature Simple Attribute

Use the temperature attribute to specify the ambient temperature in which the design is

to operate.

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Syntax

temperature : valuefloat ;

value

A floating-point number representing the ambient temperature.

tree_type Simple Attribute

Use the tree_type attribute to specify the environment interconnect model.

Syntax

tree_type : valueenum ;

value

Valid values are best_case_tree, balanced_tree, and worst_case_tree.

voltage Simple Attribute

Use the voltage attribute to specify the operating voltage of the design; typically 5 volts

for a CMOS library.

Syntax

voltage : valuefloat ;

value

A floating-point number from 0 through 1000, representing the absolute

value of the actual voltage.

power_rail Complex Attribute

Use the power_rail attribute in the operating_conditions group to specify a voltage

value for each power supply.

Syntax

power_rail (power_supply_namestring, voltage_valuefloat) ;

power_supply_name

Specifies a power supply name that can be used later for reference. You

can refer to it by assigning a string to the rail connection

input_signal_level or the output_signal_level attribute.

voltage_value

Identifies the voltage value associated with the power_supply_name.

The value is specified by the units you define in the library group

voltage_unit attribute.

Example

operating_conditions (MPSS) {

calc_mode : worst ;

process : 1.5 ;

temperature : 70 ;

voltage : 4.75 ;

tree_type : worse_case_tree ;

power_rail (VDD1, 4.8) ;

power_rail (VDD2, 2.9) ;

}

1.9.25 output_current_template Group

Use the output_current_template group to describe a table template for composite

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current source (CCS) modeling.

Syntax

library (namestring) {

output_current_template(template_nameid) {

variable_1 : valueenum ;

variable_2 : valueenum ;

variable_3 : valueenum ;

index_1 : ("float, ..., float");

index_2 : ("float, ..., float");

index_3 : ("float, ..., float");

}

Simple Attributes

variable_1

variable_2

variable_3

Complex Attributes

index_1

index_2

index_3

variable_1, variable_2, and variable_3 Simple Attributes

The table template specifying composite current source (CCS) driver and receiver models

can have three variables: variable_1, variable_2, and variable_3. The valid values

for variable_1 and variable_2 are input_net_transition and

total_output_net_capacitance. The only valid value for variable_3 is time.

index_1, index_2, and index3 Complex Attributes

Along with variable_1 and variable_2, you must specify the index values.

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

Example

library (my_library) {

...

output_current_template (CCT) {

variable_1 : input_transition ;

variable_2 : total_output_net_capacitance ;

variable_3 ; time ;

index_1 ("0.1, 0.2") ;

index_2 ("1.0, 2.0") ;

index_3 ("0.1, 0.2, 0.3, 0.4, 0.5") ;

}

...

}

1.9.26 output_voltage Group

You define an output_voltage group in the library group to designate a set of output

voltage level ranges to drive output cells.

Syntax

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library (namestring) {

output_voltage(namestring) {

vol : float | expression ;

voh : float | expression ;

vomin : float | expression ;

vomax : float | expression ;

}

output_voltage (namestring) {

... output_voltage description ... ;

}

The value for vol, voh, vomin, and vomax is a floating-point number or an expression. An

expression allows you to define voltage levels as a percentage of VSS or VDD.

vol

The maximum output voltage generated to represent a logic 0.

voh

The minimum output voltage generated to represent a logic 1.

vomin

The minimum output voltage the pad can generate.

vomax

The maximum output voltage the pad can generate.

Table 1-5 lists the predefined variables you can use in an output_voltage expression

attribute. Separate variables are defined for CMOS and BiCMOS.

Table 1-5 Voltage-Level Variables for the output_voltage Group

CMOS/BiCMOS variable Default value

VDD 5V

VSS 0V

VCC 5V

The default values represent nominal operating conditions. These values fluctuate with the

voltage range defined in the operating_conditions groups.

All voltage values are in the units you define with the voltage_unit attribute within the

library group.

Example 1-7 shows an example of an output_voltage group.

Example 1-7 output_voltage Group

output_voltage(GENERAL) {

vol : 0.4 ;

voh : 2.4 ;

vomin : -0.3 ;

vomax : VDD + 0.3 ;

}

1.9.27 part Group

You use a part group to describe a specific FPGA device. Use multiple part groups to

describe multiple devices.

Syntax

library (namestring) {

part(namestring) {

...device description...

}

part(namestring) {

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...device description...

}

Simple Attributes

default_step_level

fpga_isd

num_blockrams

num_cols

num_ffs

num_luts

num_rows

pin_count

Complex Attributes

max_count

valid_speed_grade

valid_step_level

Group

speed_grade

default_step_level Simple Attribute

Use the default_step_level attribute to specify one of the valid step levels as the

default for the FPGA device. You specify valid step levels with the valid_step_levels

complex attribute.

Syntax

default_step_level : "nameid" ;

“ name ”

An alphanumeric string identifier, enclosed within double quotation marks,

representing the default step level for the device.

Example

default_step_level ("STEP0") ;

fpga_isd Simple Attribute

Use this optional attribute to reference the drive, io_type, and slew information

contained in a library-level fpga_isd group.

Syntax

fpga_isd : fpga_isd_nameid ;

fpga_isd_name

The name of a library-level fpga_isd group.

Example

fpga_isd : part_cell_isd ;

num_blockrams Simple Attribute

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Use the num_blockrams attribute to specify the number of block select rams on the FPGA

device.

Syntax

num_blockrams : valueint ;

value

An integer representing the number of block select RAMs on the device.

Example

num_blockrams : 10 ;

num_cols Simple Attribute

Use the num_cols attribute to specify the number of logic block columns on the FPGA

device.

Syntax

num_cols : valueint ;

value

An integer representing the number of logic blocks on the FPGA device.

Example

num_cols : 30 ;

num_ffs Simple Attribute

Use the num_ffs attribute to specify the number of flip-flops on the device.

Syntax

num_ffs : valueint ;

value

An integer representing the number of flip-flops on the FPGA device.

Example

num_ffs : 2760 ;

num_luts Simple Attribute

Use the num_luts attribute to specify the total number of lookup tables available for the

FPGA device. The num_luts value is used to determine the total number of slices that

make up all the configurable logic blocks (CLBs) of the FPGA device, as shown in the

following equation.

Syntax

num_luts : valueint ;

value

An integer representing the number of lookup tables on the FPGA device.

Example

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num_luts : 100 ;

num_rows Simple Attribute

Use the num_rows attribute to specify the number of logic block rows on the FPGA device.

Syntax

num_rows : valueint ;

value

An integer representing the number of block rows on the FPGA device.

Example

num_rows : 20 ;

pin_count Simple Attribute

Use the pin_count attribute to specify the number of pins on the device.

Syntax

pin_count : valueint ;

value

An integer representing the number of pins on the FPGA device.

Example

pin_count : 94 ;

max_count Complex Attribute

Use the max_count attribute to specify the resource constraints for the FPGA device.

Syntax

max_count (resource_nameid, valueint ) ;

resource_name

The name of the resource being constrained.

value

An integer representing the maximum constraint of the resource.

Example

max_count (BUGFGTS, 4) ;

valid_speed_grade Complex Attribute

Use the valid_speed_grade attribute to specify the various speed grades for the FPGA

device.

Syntax

valid_speed_grade ("name_1id", "name_2id", ..."name_nid" ) ;

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“ name_1 ”, “ name_2 ”, “ name_n ”

A list of alphanumeric string identifiers, each enclosed within double

quotation marks, represents the various speed grades for the device. Each

identifier corresponds to an operating condition under which the library is

characterized and under which the device is used.

Example

valid_speed_grade ("-6", "-5", "-4") ;

valid_step_levels Complex Attribute

Use the valid_step_levels attribute to specify the various step levels for the FPGA

device.

Syntax

valid_step_levels ("name_1id", "name_2id", ..."name_nid" ) ;

“ name_1 ”, “ name_2 ”, “ name_n ”

A list of alphanumeric string identifiers, each enclosed within double

quotation marks, representing various step levels for the device. Each

identifier corresponds to an operating condition under which the library is

characterized and under which the device is used.

Example

valid_step_levels ("STEP0", "STEP1", "STEP2") ;

speed_grade Group

The speed_grade group associates a valid speed grade with a valid step level.

Syntax

part(namestring) {

...

speed_grade (namestring) {

...step_level description...

}

name

Specifies one of the valid speed grades listed in the valid_speed_grade

attribute.

Simple Attribute

fpga_isd

Complex Attribute

step_level

Example

speed_grade ( ) {

...

}

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fpga_isd Simple Attribute

Use this optional attribute to reference the drive, io_type, and slew information

contained in a library-level fpga_isd group.

Syntax

fpga_isd : fpga_isd_nameid ;

fpga_isd_name

The name of a library-level fpga_isd group.

Example

fpga_isd : part_cell_isd ;

step_level Complex Attribute

Use the step_level attribute to specify one of the valid step levels listed in the

valid_step_level attribute.

Syntax

step_level (namestring) ;

name

The alphanumeric identifier for a valid step level.

Example

step_level ( ) ;

1.9.28 pg_current_template Group

In the composite current source (CCS) power library format, instantaneous power data is

specified as 1- to n- dimensional tables of current waveforms in the

pg_current_template group. This library-level group creates templates of common

information that power and ground current vectors use.

Syntax

library (namestring) {

pg_current_template (template_nameid) {

... template description ...

}

Simple Attributes

variable_1

variable_2

variable_3

variable_4

Complex Attributes

index_1

index_2

index_3

index_4

variable_1, variable_2, variable_3, and variable_4 Simple Attributes

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The variable values can be input_net_transition,

total_output_net_capacitance, and time. The last variable must be time and is

required. The group can contain none or at most one input_net_transition variable. It can

contain none or up to two total_output_net_capacitance variables.

index_1, index_2, index_3, and index_4 Complex Attributes

The index values are optional.

index_1 ("float, ...") ;

index_2 ("float, ...") ;

index_3 ("float, ...") ;

index_4 ("float, ...") ;

Example

library (my_library) {

...

pg_current_template (my_template) {

variable_1 : input_net_transition ;

variable_2 : total_output_net_capacitance ;

variable_3 : total_output_net_capacitance ;

variable_4 : time ;

index_1 ("100.0000, 200.0000") ;

index_2 ("0.0, 0.0") ;

index_3 ("0.0, 0.0") ;

index_4 ("0.0, 0.0") ;

}

...

}

1.9.29 poly_template Group

Use the poly_template group to define a template of polynomials to be used by the

timing group. For reference purposes, the poly_template group requires a name.

Syntax

library (library_nameid) {

...

poly_template(poly_template_nameid) {

variables(variable_ienum, ..., variable_nenum) ;

variable_1_range(min_valuefloat, max_valuefloat) ;

...

variable_n_range(min_valuefloat, max_valuefloat) ;

mapping(valueenum, power_rail_nameid) ;

orders () ;

domain(domain_nameid) {

calc_mode : nameid ;

variables(variable_ienum, ..., variable_nenum) ;

variable_1_range(min_valuefloat, max_valuefloat) ;

...

variable_n_range(min_valuefloat, max_valuefloat) ;

mapping(valueenum, power_rail_nameid) ;

orders () ;

}

poly_template_name

The name of the template.

Complex Attributes

variables

variable_n_range

mapping

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orders

Group

domain

variables Complex Attribute

Use the variables attribute to specify the name of a variable or a list of the variables that

characterizes library cells for timing, noise immunity, and noise propagation. The variable or

variables are used in the polynomial equations.

Note:

At least one variable name is required.

Syntax

variables(variable_1enum,..., variable_nenum,) ;

variable_1 , ..., variable_n

The values depend on the group as shown in the following.

The valid variables for a noise immunity template referenced by a noise immunity

polynomial, such as noise_immunity_high, are:

input_noise_width | total_output_net_capacitance | voltage

| voltagei | temperature | parametern

The valid variables for a noise propagation template referenced by a noise propagation

group, such as propagated_noise_height_high, are:

input_noise_height | input_noise_width |

input_noise_time_to_peak | total_output_net_capacitance |

voltage, voltagei, temperature | parametern

The valid variables in a steady state group, such as steady_state_current_high, are:

iv_output_voltage | voltage | voltagei | temperature |

parametern

The valid variables in a timing group are generally divided into four sets:

● Set 1

❍ input_net_transistion | constrained_pin_transition

● Set 2

❍ total_output_net_capacitance | output_net_length,

output_net_wire_cap | output_net_pin_cap |

related_pin_transistion

● Set 3

❍ related_out_total_output_net_capacitance |

related_out_output_net_length |

related_out_output_net_wire_cap |

related_out_output_net_pin_cap

● Set 4

❍ temperature, voltage | voltage i

In Set 4, voltage is the default power supply voltage for the design and

voltage1 is normally used only when your design requires dual power supplies

for the cell; for example, for a level shifter.

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For a one-dimensional polynomial, substitute the values in Sets 1 and 2 for variable_1 . For

a two-dimensional polynomial, substitute the values in Sets 1, 2, and 4 for variable_1 and

variable_2 . For polynomials with three or more dimensions, substitute the values in Sets 1,

2, 3, and 4 for variable_1 , variable_2 , ..., variable_n .

Example

variables( temperature, voltage,

total_output_net_capacitance) ;

variable_ n _range Complex Attribute

Use the variable_ n _range attribute to specify the range of the value for the n th

variable in the variables attribute.

Note:

A variable_ n _range attribute is required for each variable listed in the variables

attribute.

Syntax

variable_n_range(float, float) ;

float , float

Floating-point number pairs that specify the value range.

Example

variable_2_range(1.5, 2.0);

mapping Complex Attribute

The mapping attribute specifies the relationship between voltage attribute (as used in

the polynomial) and the corresponding power_rail attribute defined in the

power_supply attribute.

Note:

You can have no more than two mapping attributes in a poly_template group.

Syntax

mapping(valueenum, power_rail_nameid);

value

Valid values are voltage and voltage1.

power_rail_name

Identifies the corresponding power rail.

Example

mapping(voltage, VDD2) ;

orders Complex Attribute

Use the orders attribute to specify the order for the variables for the polynomial.

Syntax

variable_n_range(float, float) ;

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Example

variable_2_range(1.5, 2.0);

domain Group

In the case of a piecewise polynomial, use one or more domain groups in the

poly_template group. The variables in a domain group are the same as the variables in

the poly_template group.

Note:

A domain name is required and the name must be unique.

Syntax

library (library_nameid) {

poly_template (poly_template_nameid) {

...

domain (domain_nameid) {

...

}

Simple Attribute

calc_mode

Complex Attributes

variables

variable_n_range

mapping

orders

calc_mode Simple Attribute

Use the calc_mode attribute to specify the associated process mode.

Syntax

calc_mode : nameid ;

name

The name of the associated process mode.

Example

calc_mode : best ;

variables, variable_ n _range, mapping, and orders Complex Attributes

For the description of how each of these attributes is used, see the “poly_template Group ” .

Example

domain (D1) {

calc_mode : best ;

variables (temperature, voltage,

total_output_net_capacitance);

variable_1_range (1.5, 2.0);

variable_2_range (1.0, 2.0);

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variable_3_range (1.0, 2.0);

mapping(voltage, VDD2) ;

}

1.9.30 power_lut_template Group

The power_lut_template group is defined within the library group, as shown here:

Syntax

library (name) {

power_lut_template (template_name) {

variable_1 : input_transition_time |

total_output_net_capacitance

|equal_or_opposite_output_net_capacitance ;

variable_2 : input_transition_time |

total_output_net_capacitance

|equal_or_opposite_output_net_capacitance ;

variable_3 : input_transition_time |

total_output_net_capacitance

|equal_or_opposite_output_net_capacitance ;

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

index_3 ("float, ..., float") ;

}

Simple Attributes

variable_1

variable_2

variable_3

Complex Attributes

index_1

index_2

index_3

Group

domain

The power_lut_template group creates a template of the index used by the

internal_power group (defined in a pin group within a cell).

The name of the template (template_name) is a name you choose that can be used later

for reference.

Note:

A power_lut_template with the name scalar is predefined; its size is 1. You can refer

to it by entering scalar as the name of a fall_power group, power group, or

rise_power group within the internal_power group (defined in the pin group).

variable_1, variable_2, and variable_3 Simple Attributes

The variable_1 attribute in the power_lut_template group specifies the first

dimensional variable used by the library developer to characterize cells in the library for

internal power.

The variable_2 attribute in the power_lut_template group specifies the second

dimensional variable the library developer uses to characterize cells in the library for

internal power.

The variable_3 attribute in the power_lut_template group specifies the third

dimensional variable the library developer uses to characterize cells in the library for

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internal power.

If the index_1 attribute is measured with the loading of the output net capacitance of the

pin specified in the pin group that contains the internal_power group (defined in a

cell group), the value for variable_1 is

equal_or_opposite_output_net_capacitance.

If the index_1 attribute is measured with the input transition time of the pin specified in the

pin group or the related_pin attribute of the internal_power group, the value for

variable_1 is input_transition_time.

If the index_2 attribute is measured with the loading of the output net capacitance of the

pin specified in the pin group that contains the internal_power group (defined in a

cell group), the value for variable_2 is

equal_or_opposite_output_net_capacitance.

If the index_2 attribute is measured with the input transition time of the pin specified in the

pin group or the related_pin attribute of the internal_power group, the value for

variable_2 is input_transition_time.

If the index_3 attribute is measured with the loading of the output net capacitance of the

pin specified in the pin group that contains the internal_power group (defined in a

cell group), the value for variable_3 is

equal_or_opposite_output_net_capacitance.

If the index_3 attribute is measured with the input transition time of the pin specified in the

pin group or the related_pin attribute of the internal_power group, the value for

variable_3 is input_transition_time.

index_1, index_2, and index_3 Complex Attributes

The index_1 complex attribute in the power_lut_template group specifies the

breakpoints of the first dimension used to characterize cells for internal power within the

library. The values specified in this attribute must be in monotonically increasing order. You

can overwrite the index_1 attribute by providing the same attribute in the fall_power

group, power group, or rise_power group within the internal_power group (defined in

the pin group). The index_1 attribute is required in the power_lut_template group.

The index_2 complex attribute in the power_lut_template group specifies the

breakpoints of the second dimension used to characterize cells for internal power within the

library. You can overwrite the index_2 attribute by providing the same attribute in the

fall_power group, power group, or rise_power group within the internal_power

group (defined in the pin group). The index_2 attribute is required in the

power_lut_template group if the variable_2 attribute is present.

The index_3 complex attribute in the power_lut_template group specifies the

breakpoints of the third dimension used to characterize cells for internal power within the

library. You can overwrite the index_3 attribute in the internal_power group by

providing the same attribute in the fall_power group, power group, or rise_power

group within the internal_power group (defined in the pin group). The index_3

attribute is required in the power_lut_template group if the variable_3 attribute is

present.

Example 1-8 shows four power_lut_template groups.

Example 1-8 Four power_lut_template Groups

power_lut_template (output_by_cap) {

variable_1 : total_output_net_capacitance ;

index_1 ("0.0, 5.0, 20.0") ;

}

power_lut_template (output_by_cap_and_trans) {

variable_1 : total_output_net_capacitance ;

variable_2 : input_transition_time ;

index_1 ("0.0, 5.0, 20.0") ;

index_2 ("0.1, 1.0, 5.0") ;

}

power_lut_template (input_by_trans) {

variable_1 : input_transition_time ;

index_1 ("0.0, 1.0, 5.0") ;

}

power_lut_template (output_by_cap2_and_trans) {

variable_1 : total_output_net_capacitance ;

variable_2 : input_transition_time ;

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variable_3 : equal_or_opposite_output_net_capacitance ;

index_1 ("0.0, 5.0, 20.0") ;

index_2 ("0.1, 1.0, 5.0") ;

index_3 ("0.1, 0.5, 1.0") ;

}

Use the report_lib -timing command to report power_lut_template information

in the library. You can do this only while reading in the library source file in the same

session. The report will resemble the one shown in Example 1-9.

Example 1-9 power_lut_template Report

Internal Power Lookup Template:

Template_name variable_1 variable_2

------------------------------------------------------------------------------

output_by_cap total_output_net_capacitance

index_1 : 0.0000 5.0000 20.0000

output_by_cap_and_trans total_output_net_capacitance input_transition_time

index_1 : 0.0000 5.0000 20.0000

index_2 : 0.1000 1.0000 5.0000

input_by_trans input_transition_time

index_1 : 0.0000 1.0000 5.0000

output_by_cap2_and_trans equal_or_opposite_output_net_capacitance

index_1 : 0.0000 5.0000 20.0000

index_2 : 0.1000 1.0000 5.0000

index_3 : 0.1000 0.5000 1.0000

domain Group

In the case of a piecewise polynomial, use one or more domain groups in the

power_lut_template group. The variables in a domain group are the same as the

variables in the power_lut_template group. For more information about using a

domain group, see “domain Group ” .

1.9.31 power_poly_template Group

Use the power_poly_template group to define a template of polynomials to be used by

the timing group. For reference purposes, the power_poly_template group requires a

name.

Syntax

library (library_nameid) {

...

power_poly_template(power_poly_template_nameid) {

variables(variable_ienum, ..., variable_nenum) ;

variable_1_range(min_valuefloat, max_valuefloat) ;

...

variable_n_range(min_valuefloat, max_valuefloat) ;

mapping(valueenum, power_rail_nameid) ;

domain(domain_nameid) {

calc_mode : nameid ;

variables(variable_ienum, ..., variable_nenum) ;

variable_1_range(min_valuefloat, max_valuefloat) ;

...

variable_n_range(min_valuefloat, max_valuefloat) ;

mapping(valueenum, power_rail_nameid) ;

}

power_poly_template_name

The name of the template.

Complex Attributes

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variables

variable_n_range

mapping

Group

domain

variables Complex Attribute

Use the variables attribute to specify the name of a variable or a list of the variables that

characterize library cells for power; that is, the variables used in the polynomial equations.

Note:

At least one variable name is required. A maximum of seven variables is allowed.

Syntax

variables(variable_1enum,..., variable_nenum,) ;

variable_1 , ..., variable_n

Valid values for polynomial variables are:

equal_or_opposite_output_net_capacitance, input_net_transition,

total_output_net_capacitance, output_net_length, temperature, voltage,

voltage i , and parameter i .

Example

variables( temperature, voltage,

total_output_net_capacitance) ;

variable_ n _range Complex Attribute

Use the variable_ n _range attribute to specify the range of the value for the n th

variable in the variables attribute.

Note:

A variable_ n _range attribute is required for each variable listed in the variables

attribute.

Syntax

variable_n_range(value_1float, value_2float) ;

value_1 , value_2

Floating-point number pairs that specify the value range.

Example

variable_2_range(1.5, 2.0);

mapping Complex Attribute

The mapping attribute specifies the relationship between the voltage attribute (as used

in the polynomial) and the corresponding power_rail attribute defined in the

power_supply attribute.

Note:

You can have no more than two mapping attributes in a power_poly_template group.

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Syntax

mapping(valueenum, power_rail_nameid);

value

Valid values are voltage and voltage1.

power_rail_name

Identifies the corresponding power rail.

Example

mapping(voltage, VDD2) ;

domain Group

In the case of a piecewise polynomial, use one or more domain groups in the

poly_template group. The variables in a domain group are the same as the variables in

the poly_template group.

Note:

A domain name is required and the name must be unique.

Syntax

library (library_nameid) {

power_poly_template (power_poly_template_nameid) {

...

domain (domain_nameid) {

...

}

Simple Attribute

calc_mode

Complex Attributes

variables

variable_n_range

mapping

calc_mode Simple Attribute

Use the calc_mode attribute to specify the associated process mode.

Syntax

calc_mode : nameid ;

name

The name of the associated process mode.

variables, variable_ n _range, and mapping Complex Attributes

For the description of how each of these attributes is used, see the “poly_template Group ” .

1.9.32 power_supply Group

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The power_supply group is defined in the library group, as shown here:

library (name) {

power_supply (name) {

default_power_rail : string ;

power_rail(power_supply_namestring,voltage_valuefloat)

...

}

Simple Attribute

default_power_rail

Complex Attribute

power_rail

The power_supply group captures all nominal information on voltage variation.

default_power_rail Simple Attribute

The default_power_rail attribute receives, by default, the value of the voltage

attribute defined in the nominal operating_conditions group.

Syntax

default_power_rail : power_supply_namestring ;

power_supply_name

An identifier for the power supply.

Example

default_power_rail : VDD0 ;

power_rail Complex Attribute

The power_rail attribute identifies all power supplies that have the nominal operating

conditions (defined in the operating_conditions group) and the nominal voltage

values. The power_supply group can define one or more power_rail attributes.

Syntax

power_rail (power_supply_namestring,voltage_valuefloat)

power_supply_name

Specifies a power supply name that can be used later for reference. You

can refer to it by assigning a string to the rail connection

input_signal_level or output_signal_level attribute.

voltage_value

A floating-point number that identifies the voltage value associated with the

power_supply_name . The value is in the units you define within the

library group voltage_unit attribute.

Example

power_rail (VDD1, 5.0) ;

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Example 1-10 shows a library containing a power_supply group.

Example 1-10 Library Example With power_supply Group

library (multiple_power_supply) {

power_supply ( ) {

/* Define before operating conditions and cells. */

default_power_rail : VDD0 ;

power_rail (VDD1, 5.0) ;

power_rail (VDD2, 3.3) ;

...

}

Multiple Power Supply Library Requirements

Use the report_lib -power command to report multiple power supply information in the

library. The report will resemble the one shown in Example 1-11.

Example 1-11 Multiple Power Supply Report

Power Supply Group:

default_power_rail : VDD0

power Rail Value

--------------------

VDD1 5.00

VDD2 3.30

Power Rail in the Operating Conditions Groups:

Name : MPSS

power Rail Value

--------------------

VDD1 4.80

VDD2 2.90

Power Rail Connection Information:

Name : IBUF1

RAIL CONNECTION(PV1): VDD1

RAIL CONNECTION(PV2): VDD2

Signal Level Information:

CELL(IBUF1):

PIN(A):

INPUT_SIGNAL_LEVEL(A): VDD1

END_PIN A;

PIN(EN):

INPUT_SIGNAL_LEVEL(EN): VDD1

END_PIN EN;

PIN(Z):

OUTPUT_SIGNAL_LEVEL(Z): VDD2

END_PIN Z;

PIN(Z1):

INPUT_SIGNAL_LEVEL(Z1): VDD1

OUTPUT_SIGNAL_LEVEL(Z1): VDD2

END_PIN Z1;

END_CELL IBUF1;

1.9.33 propagation_lut_template Group

The propagation_lut_template group defines a template for specifying noise

propagation through a cell.

Syntax

library (namestring) {

propagation_lut_template (template_namestring) {

... template description ...

}

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}

Simple Attributes

variable_1

variable_2

variable_3

Complex Attributes

index_1

index_2

index_3

variable_1, variable_2, and variable_3 Simple Attributes

The values you can assign to variable_1 and variable_2 are input_noise_width,

input_noise_height, and total_output_net_capacitance.

index_1, index_2, and index_3 Complex Attributes

Along with variable_1, variable_2, and variable_3, you must define index_1, index_2, and

index_3

index_1 ("float, ..., float");

index_2 ("float, ..., float");

index_3 ("float, ..., float");

Example

library (my_library) {

...

propagation_lut_template (my_template) {

variable_1 : input_noise_width ;

variable_2 : input_noise_height ;

variable_3 : total_output_net_capacitance ;

index_1 ("0.01, 0.2, 2") ;

index_2 ("0.2, 0.8") ;

index_2 ("0, 2") ;

}

...

}

1.9.34 rise_net_delay Group

The rise_net_delay group is defined at the library level, as shown here:

library (name) {

rise_net_delay(name) {

... rise net delay description ...

}

fall_net_delay (name){

... fall net delay description ...

}

Complex Attributes

index_1 ("float,...,float") ;

index_2 ("float,...,float") ;

values ("float,...,float","float,...,float");

The rise_net_delay and the fall_net_delay groups define, in the form of lookup

tables, the values for rise and fall net delays. This indexing allows the library developer to

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model net delays as any function of output_transition and rc_product.

The net delay tables in one library have no effect on computations related to cells from

other libraries.

To overwrite the lookup table default index values, specify the new index values before the

net delay values, as shown in the following examples.

Example 1-12 shows an example of the rise_net_delay group.

Example 1-12 rise_net_delay Group

rise_net_delay (net_delay_template_table) {

index_1 ("0, 1, 2") ;

index_2 ("1, 0, 2") ;

values ("0.00, 0.21", "0.11, 0.23") ;

}

See also fall_net_delay Group .

1.9.35 rise_transition_degradation Group

The rise_transition_degradation group is defined at the library level, as shown

here:

library (name) {

rise_transition_degradation(name) {

... rise transition degradation description ...

}

Complex Attributes

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

values ("float, ..., float", "float, ...,float") ;

The rise_transition_degradation group and the

fall_transition_degradation group describe, in the form of lookup tables, the

transition degradation functions for rise and fall transitions. The lookup tables are indexed

by the transition time at the net driver and the connect delay between the driver and a

particular load. This indexing allows the library developer to model degraded transitions as

any function of output-pin transition and connect delay between the driver and the load.

Transition degradation tables are used for indexing into any delay table in a library that has

the input_net_transition, constrained_pin_transition, or

related_pin_transition table parameters in the lu_table_template group.

The transition degradation tables in one library have no effect on computations related to

cells from other libraries. Example 1-13 and shows an example of the

rise_transition_degradation group.

Example 1-13 rise_transition_degradation Group

rise_transition_degradation (trans_deg) {

index_1 ("0, 1, 2") ;

index_2 ("1, 0, 2") ;

values ("0.0, 0.6", "1.0, 1.6") ;

}

See also “fall_transition_degradation Group ” .

1.9.36 scaled_cell Group

You define a scaled_cell group within the library group to supply an alternative set of

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values for an existing cell, based on the set of operating conditions used.

Operating conditions are defined in the “operating_conditions Group” .

Syntax

scaled_cell (existing_cell, operating_conditions_group) {

... scaled cell description ...

}

existing_cell

The name of a cell defined in a previous cell group.

operating_conditions_group

The library-level operating_conditions group with which the scaled

cell is associated.

Simple Attributes

The following attributes are also defined in the cell group.

area : float ;

auxiliary_pad_cell : true | false ;

bus_naming_style : "string" ;

cell_footprint : footprint_typestring ;

cell_leakage_power : float ;

clock_gating_integrated_cell : string_value ;

contention_condition: "Boolean expression" ;

dont_fault : sa0 | sa1 | sa01 ;

dont_touch : true | false ;

dont_use : true | false ;

geometry_print : string ;

handle_negative_constraint : true | false;

is_clock_gating_cell : true | false ;

map_only : true | false ;

pad_cell : true | false ;

pad_type : clock ;

preferred : true | false ;

scaling_factors : group_name ;

single_bit_degenerate : string ;

/* black box, bus, and bundle cells only*/

use_for_size_only : true | false ;

vhdl_name : "string" ;

Complex Attributes

The following attributes are also defined in the cell group.

pin_equal ("name_liststring") ;

pin_opposite ("name_list1string","name_list2string") ;

rail_connection (connection_namestring,

power_supply_namestring) ;

Group Statements

The following groups are also defined in the cell group.

bundle

bus

ff

ff_bank

generated_clock

latch

latch_bank

leakage_power

lut

mode_definition

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routing_track

statetable

test_cell

type

1.9.37 sensitization Group

The sensitization group defined at the library level describes the complete state

patterns for a specific list of pins (defined by the pin_names attribute) that will be

referenced and instantiated as stimuli in the timing arc.

Vector attributes in the group define all possible pin states used as stimuli. Actual stimulus

waveforms can be described by a combination of these vectors. Multiple sensitization

groups are allowed in a library. Each sensitization group can be referenced by multiple

cells, and each cell can make reference to multiple sensitization groups.

Syntax

library(library_name) {

...

sensitization (sensitization_group_name) {

...

}

Complex Attributes

pin_names

vector

1.9.38 pin_names Complex Attribute

The pin_names attribute specified at the library level defines a default list of pin names. All

vectors in this sensitization group are the exhaustive list of all possible transitions of

the input pins and their subsequent output response.

The pin_names attribute is required, and it must be declared in the sensitization

group before all vector declarations.

Syntax

pin_names (string..., string);

Example

pin_names (IN1, IN2, OUT);

1.9.39 vector Complex Attribute

Similar to the pin_names attribute, the vector attribute describes a transition pattern for

the specified pins. The stimulus is described by an ordered list of vectors.

The arguments for the vector attribute are as follows:

vector id

The vector id argument is an identifier to the vector string (a number

tag that defines the list of possible sensitization combinations in a cell). The

vector id value must be an integer greater than or equal to zero and

unique among all vectors in the current sensitization group. It is

recommended that you start numbering from 0 or 1.

vector string

The vector string argument represents a pin transition state.The string

consists of the following transition status values: 0, 1, X, and Z where each

character is separated by a space. The number of elements in the vector

string must equal the number of arguments in pin_names.

The vector attribute can also be declared as:

vector (positive_integer, "{0|1|X|Z} [0|1|X|Z]…");

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Syntax

vector (integer, string);

Example

sensitization(sensitization_nand2) {

pin_names ( IN1, IN2, OUT1 );

vector ( 1, "0 0 1" );

vector ( 2, "0 1 1" );

vector ( 3, "1 0 1" );

vector ( 4, "1 1 0" );

1.9.40 scaling_factors Group

A scaling_factors group is defined within the library group. .

Syntax

library (namestring) {

scaling_factors ("namestring") {

... scaling factors ...

}

Simple Attributes

The scaling_factors group uses the simple scaling attributes (that is, those with the k_

prefix ) included in Example 1-1.

1.9.41 timing Group

A timing group is defined in a bundle, a bus, or a pin group within a cell. The timing

group can be used to identify the name or names of multiple timing arcs. A timing group

identifies multiple timing arcs, by identifying a timing arc in a pin group that has more than

one related pin or when the timing arc is part of a bundle or a bus.

The following syntax shows a timing group in a pin group within a cell group.

Syntax

library (namestring) {

cell (name) {

pin (name) {

timing (name | name_list) {

... timing description ...

}

1.9.42 timing_range Group

Use the timing_range group to specify scaling factors that control signal arrival time.

Syntax

library (namestring) {

timing_range (namestring) {

... timing range description ...

}

Simple Attributes

faster_factor

slower_factor

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faster_factor Simple Attribute

Use this attribute to specify a scaling factor to apply to the signal arrival time to model the

fastest-possible arrival time.

Syntax

faster_factor : valuefloat ;

value

A floating-point number representing the scaling factor.

Example

faster_factor: 0.0 ;

slowest_factor Simple Attribute

Use this attribute to specify a scaling factor to apply to the signal arrival time to model the

slowest-possible arrival time.

Syntax

slowest_factor : valuefloat ;

value

A floating-point number representing the scaling factor.

Example

slowest_factor: 0.0 ;

1.9.43 type Group

If your library contains bused pins, you must define type groups and define the structural

constraints of each bus type in the library. The type group is defined at the library

group level, as shown here:

Syntax

library (namestring) {

type (name) {

... type description ...

}

name

Identifies the bus type.

Simple Attributes

base_type : base ;

bit_from : integer ;

bit_to : integer ;

bit_width : integer ;

data_type : data ;

downto : true | false ;

base_type : base ;

Only the array base type is supported.

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bit_from : integer ;

Indicates the member number assigned to the most significant bit (MSB) of

successive array members. The default is 0.

bit_to : integer ;

Indicates the member number assigned to the least significant bit (LSB) of

successive array members. The default is 0.

bit_width : integer ;

Designates the number of bus members. The default is 1.

data_type : data ;

Indicates that only the bit data type is supported.

downto : true | false ;

A true value indicates that member number assignment is from high to low.

A false value indicates that member number assignment is from low to high.

Example 1-14 illustrates a type group statement.

Example 1-14 type Group Description

type (BUS4) {

base_type : array ;

bit_from : 0 ;

bit_to : 3 ;

bit_width : 4 ;

data_type : bit ;

downto : false ;

}

It is not necessary to use all attributes. .

Example 1-15 Alternative type Group Descriptions

type (BUS4) {

base_type : array ;

data_type : bit ;

bit_width : 4 ;

bit_from : 0 ;

bit_to : 3 ;

}

type (BUS4) {

base_type : array ;

data_type : bit ;

bit_width : 4 ;

bit_from : 3 ;

downto : true ;

}

After you define a type group, you can use it in a bus group to describe bused pins.

1.9.44 user_parameters Group

Use the user_parameters group to specify default values for up to five user-defined

process variables.

You define a user_parameters group in a library group as follows.

Syntax

library (name) {

user_parameters () {

... parameter descriptions...

}

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Simple Attributes

parameteri

parameter i Simple Attributes

Use each generic attribute to specify a default value for a user-defined process variable.

You can specify up to five variables.

Syntax

parameteri : valuefloat ;

value

A floating-point number representing a variable value.

Example

parameter1: 0.5 ;

1.9.45 wire_load Group

A wire_load group is defined in a library group, as follows.

Syntax

library (name) {

wire_load (name) {

... wire load description ...

}

Simple Attributes

area : float ;

capacitance : float ;

resistance : float ;

slope : float ;

Complex Attribute

fanout_length

area Simple Attribute

Use this attribute to specify area per unit length of interconnect wire.

Syntax

area : valuefloat ;

value

A floating-point number representing the area.

Example

area: 0.5 ;

capacitance Simple Attribute

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Use this attribute to specify capacitance per unit length of interconnect wire.

Syntax

capacitance : valuefloat ;

value

A floating-point number representing the capacitance.

Example

capacitance : 1.2 ;

resistance Simple Attribute

Use this attribute to specify wire resistance per unit length of interconnect wire.

Syntax

resistance : valuefloat ;

value

A floating-point number representing the resistance.

Example

resistance : 0.001 ;

slope Simple Attribute

Use this attribute to characterize linear fanout length behavior beyond the scope of the

longest length specified in the fanout_length attribute.

Syntax

slope : valuefloat ;

value

A floating-point number representing the slope in units per fanout.

Example

slope : 0.186

fanout_length Complex Attribute

Use this attribute to define values for fanout and length when you create the wire load

manually. The create_wire_load command generates these values automatically.

Syntax

fanout_length(fanoutint,lengthfloat,average_capacitancefloat,\

standard_deviationfloat,number_of_netsint) ;

fanout

An integer representing the total number of pins, minus one, on the net

driven by the given output.

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length

A floating-point number representing the estimated amount of metal that is

statistiacally found on a network with the given number of pins.

Examples

library (example)

...

wire_load (small) {

area : 0.0 ;

capacitance : 1.0 ;

resistance : 0.0 ;

slope : 0.0 ;

fanout_length (1,1.68) ;

}

library (example) {

...

wire_load ("90x90") {

lu_table_template (wire_delay_table_template) {

variable_1 : fanout_number;

variable_2 : fanout_pin_capacitance;

variable_3 : driver_slew;

index_1("0.12,3.4");

index_2("0.12,4.24");

index_3("0.1,2.7,3.12");

}

1.9.46 wire_load_selection Group

A wire_load_selection group is defined in a library group, as follows.

Syntax

library (name) {

wire_load_selection (name) {

... wire load selection criteria ...

}

Complex Attribute

wire_load_from_area (float, float, string) ;

Example

wire_load_selection (normal) {

wire_load_from_area (100, 200, average) ;

}

1.9.47 wire_load_table Group

A wire_load_table group is defined in a library group, as follows.

Syntax

library (name) {

wire_load_table (name) {

... wire_load table description ...

}

Complex Attributes

fanout_area (integer, float) ;

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fanout_capacitance (integer, float) ;

fanout_length (integer, float) ;

fanout_resistance (integer, float) ;

Example

library (wlut) {

wire_load_table ("05x05") {

fanout_area (1, 0.2) ;

fanout_capacitance (1, 0.15);

fanout_length (1, 0.2) ;

fanout_resistance (1, 0.17) ;

}

2. cell and model Group Description and Syntax

Every cell in a library has a separate cell description (a cell group) within the library

group. A cell group can contain simple and complex attributes and other group

statements.

Every model in a library also has a separate model description (a model group) within the

library group. A model group can include the same simple and complex attributes and

group statements as a cell group, plus two new attributes that can be used only in the

model group.

This chapter describes the attributes and groups that can be included within cell and

model groups, with the exception of the pin group, which is described in Chapter 3, “pin

Group Description and Syntax.”

This chapter is organized as follows:

● cell Group

❍ Attributes and values

❍ Simple attributes

❍ Complex attributes

❍ Group statements

● model Group

❍ Attributes and values

Within each division, the attributes and group statements are presented alphabetically.

2.1 cell Group

A cell group is defined within a library group, as shown here:

library (namestring) {

cell (namestring) {

... cell description ...

}

2.1.1 Attributes and Values

Example 2-1 lists alphabetically all the attributes and groups that you can define within a

cell group.

Example 2-1 Attributes and Values for a cell Group

/* Simple Attributes for cell group */

area : float ;

auxiliary_pad_cell : true | false ;

base_name : cell_base_namestring ;

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bus_naming_style : "string" ;

cell_footprint : footprint_typestring ;

cell_leakage_power : float ;

clock_gating_integrated_cell : string_value ;

contention_condition: "Boolean expression" ;

dont_fault : sa0 | sa1 | sa01 ;

dont_touch : true | false ;

dont_use : true | false ;

driver_type : nameid ;

edif_name: nameid ;

em_temp_degradation_factor : valuefloat ;

fpga_domain_style : nameid ;

geometry_print : string ; /* bus and bundle cells only */

handle_negative_constraint : true | false;

interface_timing : true | false ;

io_type : nameid ;

is_clock_gating_cell : true | false ;

map_only : true | false ;

pad_cell : true | false ;

pad_type : clock ;

power_cell_type : ;

preferred : true | false ;

scaling_factors : group_name ;

single_bit_degenerate : string ;

/* black box, bus, and bundle cells only*/

slew_type : nameid ;

timing_model_type : "string" ;

use_for_size_only : true | false ;

vhdl_name : "string" ;

/* Complex Attributes for cell Group */

pin_equal ("name_liststring") ;

pin_opposite ("name_list1string","name_list2string") ;

rail_connection (connection_namestring,

power_supply_namestring) ;

resource_usage (resource_nameid, number_of_resourcesid);

/* Group Statements for cell Group */

bundle (namestring) { }

bus (namestring) { }

dynamic_current () {}

ff (variable1string, variable2string) { }

ff_bank (variable1string, variable2string, bitsinteger) { }

functional_yield_metric () {}

generated_clock () {}

intrinsic_parasitic () {}

latch (variable1string, variable2string) { }

latch_bank (variable1string, variable2string, bitsinteger) { }

leakage_current () {}

leakage_power () { }

lut (namestring) { }

mode_definition () {}

pin (namestring | name_liststring) { }

routing_track (routing_layer_namestring) { }

statetable ("input node names", "internal node names") { }

test_cell () { }

type (namestring) { }

Descriptions of the attributes and group statements follow.

2.1.2 Simple Attributes

This section lists, alphabetically, the simple attributes for the cell and model groups.

auxiliary_pad_cell Simple Attribute

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See “pad_cell Simple Attribute” .

base_name Simple Attribute

Use the base_name attribute to define a name for the output cell generated by VHDL or

Verilog. If you omit this attribute, the cell is given the name "io_cell_name".

Syntax

base_name : "cell_base_nameid" ;

cell_base_name

An alphanumeric string, enclosed in quotation marks, representing a name

for the output cell.

Example

base_name : "IBUF" ;

bus_naming_style Simple Attribute

Use the bus_naming_style attribute to define the naming convention for buses in the

library.

Syntax

bus_naming_style : "string" ;

Example

bus_naming_style : "Bus%sPin%d" ;

cell_footprint Simple Attribute

Use the cell_footprint attribute to assign a footprint class to a cell.

Syntax

cell_footprint : class_nameid ;

class_name

A character string that represents a footprint class. The string is case-

sensitive: And4 is different footprint from and4.

Example

cell_footprint : 5MIL ;

Use this attribute to assign the same footprint class to all cells that have the same

geometric layout characteristics.

Cells with the same footprint class are considered interchangeable and can be swapped

during in-place optimization. Cells without cell_footprint attributes are not swapped

during in-place optimization.

When you use cell_footprint, you also set the in_place_swap_mode attribute to

match_footprint.

cell_leakage_power Simple Attribute

Use the cell_leakage_power attribute to define the leakage power of a cell. If missing

or negative, the value of the default_cell_leakage_power attribute defined in the

library is assumed.

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Syntax

cell_leakage_power : valuefloat ;

value

A floating-point number indicating the leakage power of the cell.

Example

cell_leakage_power : 0.2

The cell_leakage_power attribute is also recognized in the scaled_cell group,

where it allows you to model nonlinear scaling of leakage power relative to certain process,

voltage, and temperature conditions.

clock_gating_integrated_cell Simple Attribute

You can use the clock_gating_integrated_cell attribute to enter specific values

that determine which integrated cell functionality the clock-gating software uses.

Syntax

clock_gating_integrated_cell:generic|valueid;

generic

When specified, the actual value is determinedby accessing the state

tables and state functions of the library cell pins.

value

A concatenation of up to four strings that describe the functionality of the

cell to the clock-gating software:

The first string specifies the type of sequential element you want. The

options are latch-gating logic, flip-flop gating logic, and none.

The second string specifies whether the logic is appropriate for rising- or

falling-edge-triggered registers. The options are posedge and negedge.

The third (optional) string specifies whether you want test control logic

located before or after the latch or flip-flop, or not at all. The options for

cells set to latch or flip-flop are precontrol (before), postcontrol (after), or no

entry. The options for cells set to no gating logic are control and no entry.

The fourth (optional) string, which exists only if the third string does,

specifies whether you want observability logic or not. The options are obs

and no entry. Table 2-1 lists some example values for the

clock_gating_integrated_cell attribute:

Table 2-1 Some Values for the clock_gating_integrated_cell Attribute

Value of clock_gating_integrated_cell Integrated cell must contain

latch_negedge 1. Latch-based gating logic2. Logic appropriate for

falling-edge-triggered registers

latch_posedge_postcontrol 1. Latch-based gating logic2. Logic appropriate for

rising-edge-triggered registers3. Test control logic

located after the latch

latch_negedge_precontrol 1. Latch-based gating logic2. Logic appropriate for

falling-edge- triggered registers3. Test control logic

located before the latch

none_posedge_control_obs 1. Latch-free gating logic2. Logic appropriate for rising-

edge-triggered registers3. Test control logic (no latch)

4. Observability logic

For more details about the clock-gating integrated cells, see the “Modeling Power and

Electromigration” chapter in the Liberty User Guide, Volume 1.

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Example

clock_gating_integrated_cell : latch_posedge_precontrol_obs ;

Setting Pin Attributes for an Integrated Cell

The clock-gating software requires setting the pins of your integrated cells using the

attributes listed in Table 2-2. Setting some of the pin attributes, such as those for test and

observability, is optional.

Table 2-2 Pin Attributes for Integrated Clock Gating Cells

Integrated cell pin name Data direction Required attribute

clock in clock_gate_clock_pin

enable in clock_gate_enable_pin

test_mode or scan_enable

in clock_gate_test_pin

enable_clock out clock_gate_out_pin

Setting Timing for an Integrated Cell

You set both the setup and hold arcs on the enable pin by setting the

clock_gate_enable_pin attribute for the integrated cell to true. The setup and hold arcs

for the cell are determined by the edge values you enter for the

clock_gating_integrated_cell attribute. Table 2-3 lists the edge values and the

corresponding setup and hold arcs.

Table 2-3 Values of the clock_gating_integrated_cell Attribute

Value of clock_gating_integrated_cell attribute Setup arc Hold arc

latch_posedge rising rising

latch_negedge falling falling

none_posedge falling rising

none_negedge rising falling

contention_condition Simple Attribute

Specifies the contention conditions for a cell. Contention is a clash of “0” and “1” signals. In

certain cells, it may be a forbidden condition and cause circuits to short.

Syntax

contention_condition : "Boolean expression" ;

Example

contention_condition : "ap * an" ;

dont_fault Simple Attribute

This attribute is used by test tools. It is a string attribute that you can set on a library cell or

pin.

Syntax

dont_fault : sa0 | sa1 | sao1 ;

sa0, sa1, sa01

The value you enter determines whether the dont_fault attribute will be

placed on stuck at 0 (sa0), stuck at 1 (sa1), or stuck on both faults (sa01).

Example

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dont_fault : sa0 ;

The dont_fault attribute can also be defined in the pin group.

dont_touch Simple Attribute

The dont_touch attribute with a true value indicates that all instances of the cell must

remain in the network.

Syntax

dont_touch : valueBoolean ;

value

Valid values are true and false.

Example

dont_touch : true ;

In addition to defining dont_touch in a cell group or a model group, you can also apply

the dont_touch attribute to a cell, by using the set_dont_touch command.

dont_use Simple Attribute

The dont_use attribute with a true value indicates that a cell should not be added to a

design during optimization.

Syntax

dont_use : valueBoolean ;

value

Valid values are true and false.

Example

dont_touch : true ;

In addition to defining dont_touch in a cell group or a model group, you can also apply

the dont_touch attribute to a cell, by using the set_dont_touch command.

driver_type Simple Attribute

Use the driver_type attribute to specify the drive power of the output or the I/O cell.

Syntax

driver_type : nameid ;

name

An alphanumeric string identifier, enclosed in quotation marks,

representing the drive power.

Example

driver_type : "4" ;

driver_waveform Simple Attribute

The driver_waveform attribute is an optional string attribute that allows you to define a

cell-specific driver waveform. The value must be the driver_waveform_name predefined

in the normalized_driver_waveform table.

When the attribute is defined, the cell uses the specified driver waveform during

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characterization. When it is not specified, the common driver waveform (the

normalized_driver_waveform table without the driver_waveform_name attribute)

is used for the cell.

Syntax

cell (cell_name) {

…

driver_waveform : string;

driver_waveform_rise : string;

driver_waveform_fall : string;

Example

cell (my_cell1) {

driver_waveform : clock_driver;

…

}

cell (my_cell2) {

driver_waveform : bus_driver;

…

}

cell (my_cell3) {

driver_waveform_rise : rise_driver;

driver_waveform_fall : fall_driver;

…

}

driver_waveform_rise and driver_waveform_fall Simple Attributes

The driver_waveform_rise and driver_waveform_fall string attributes are similar

to the driver_waveform attribute. These two attributes allow you to define rise-specific

and fall-specific driver waveforms. The driver_waveform attribute can coexist with the

driver_waveform_rise and driver_waveform_fall attributes, though the

driver_waveform attribute becomes redundant.

You should specify a driver waveform for a cell by using the following priority:

● Use the driver_waveform_rise for a rise arc and the

driver_waveform_fall for a fall arc during characterization. If they are not

defined, specify the second and third priority driver waveforms.

● Use the cell-specific driver waveform (defined by the driver_waveform

attribute).

● Use the library-level default driver waveform (defined by the

normalized_driver_waveform table without the driver_waveform_name

attribute).

The driver_waveform_rise attribute can refer to a normalized_driver_waveform

that is either rising or falling. It is possible to invert the waveform automatically during

runtime if necessary.

Syntax

cell (cell_name) {

…

driver_waveform : string;

driver_waveform_rise : string;

driver_waveform_fall : string;

Example

cell (my_cell1) {

driver_waveform : clock_driver;

…

}

cell (my_cell2) {

driver_waveform : bus_driver;

…

}

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cell (my_cell3) {

driver_waveform_rise : rise_driver;

driver_waveform_fall : fall_driver;

…

}

edif_name Simple Attribute

Use the edif_name attribute to define the name of the output cell generated by EDIF. If

you omit this attribute, the cell is given the name "io_cell_name".

Syntax

edif_name : nameid ;

name

An alphanumeric string, enclosed in quotation marks, representing a name

for the output EDIF cell.

Example

edif_name : "OBUF" ;

em_temp_degradation_factor Simple Attribute

The em_temp_degradation_factor attribute specifies the electromigration exponential

degradation factor.

Syntax

em_temp_degradation_factor : valuefloat ;

value

A floating-point number in centigrade units consistent with other

temperature specifications throughout the library.

Example

em_temp_degradation_factor : 40.0 ;

fpga_cell_type Simple Attribute

Specifies whether a tool interprets a combination timing arc between the clock pin and the

output pin as a rising edge arc or as a falling edge arc.

Syntax

fpga_cell_type : valueenum ;

value

Valid values are rising_edge_clock_cell and

falling_edge_clock_cell.

Example

fpga_cell_type : rising_edge_clock_cell ;

fpga_domain_style Simple Attribute

Use this attribute to reference a calc_mode value in a domain group in a polynomial

table.

Syntax

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fpga_domain_style : "nameid" ;

name

The calc_mode value.

Example

fpga_domain_style : "speed";

fpga_isd Simple Attribute

Use the fpga_isd attribute to reference the drive, io_type, and slew information

contained in a library-level fpga_isd group.

Syntax

fpga_isd : fpga_isd_nameid ;

fpga_isd_name

The name of the library-level fpga_isd group.

Example

fpga_isd : part_cell_isd ;

geometry_print Simple Attribute

The geometry_print attribute specifies certain bundle or bus multibit cells so that they

can be sizedtogether for layout requirements. At least two cells in the library must have the

same name defined by this attribute, such as GP1 in the following example.

Syntax

geometry_print : cell_nameid ;

cell_name

A character string identifying two or more bus or bundle cells in a library.

Example

cell (FDX2) {

area : 18 ;

geometry_print : GP1 ;

bundle (D) {

members (D0, D1) ;

direction : input ;

...

timing ( ) {

...

}

cell (FDX4) {

area : 32 ;

geometry_print : GP1 ;

bundle (E) {

members (D1, D0) ;

direction : input ;

...

timing ( ) {

...

}

handle_negative_constraint Simple Attribute

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You use this attribute during generation of VITAL models to indicate whether a cell needs

negative constraint handling. It is an optional attribute for timing constraints in a cell or

model group.

Syntax

handle_negative_constraint : true | false ;

Example

handle_negative_constraint : true ;

interface_timing Simple Attribute

Indicates that the timing arcs are interpreted according to interface timing specifications

semantics. If this attribute is missing or its value is set to false, the timing relationships are

interpreted as those of a regular cell rather than according to interface timing specification

semantics.

Syntax

interface_timing : true | false ;

The following example shows a cell with interface_timing set to true, indicating that

interface timing semantics are to be applied.

Example

interface_timing : true ;

io_type Simple Attribute

Use the io_type attribute to define the I/O standard used by this I/O cell.

Syntax

io_type : nameid ;

name

An alphanumeric string identifier, enclosed in quotation marks,

representing the I/O standard.

Example

io_type : "LVTTL" ;

is_clock_gating_cell Simple Attribute

The cell-level is_clock_gating_cell attribute specifies that a cell is for clock gating.

Syntax

is_clock_gating_cell : true | false ;

Example

is_clock_gating_cell : true;

Set this attribute only on 2-input AND, NAND, OR, and NOR gates; inverters; buffers; and 2-

input D latches.

is_isolation_cell Simple Attribute

The cell-level is_isolation_cell attribute specifies that a cell is an isolation cell. The

pin-level isolation_cell_enable_pin attibute specifes the enable input pin for the

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isolation cell.

Syntax

is_isolation_cell : Boolean expression ;

Boolean expression

Valid values are true and false.

Example

is_isolation_cell : true ;

is_level_shifter Simple Attribute

The cell-level is_level_shifter attribute specifies that a cell is a level shifter cell. The

pin-level level_shifter_enable_pin attibute specifes the enable input pin for the level

shifter cell.

Syntax

is_level_shifter : Boolean expression ;

Boolean expression

Valid values are true and false.

Example

is_level_shifter : true ;

level_shifter_type Simple Attribute

The level_shifter_type attribute specifies the voltage conversion type that is

supported. Valid values are:

LH

Low to High

HL

High to Low

HL_LH

High to Low and Low to High

The level_shifter_type attribute is optional.

Syntax

level_shifter_type : level_shifter_type_value ;

Example

level_shifter_type : HL_LH ;

map_only Simple Attribute

The map_only attribute with a true value indicates that a cell is excluded from logic-level

optimization during compilation.

Syntax

map_only : true | false ;

In addition to defining map_only in a cell group or a model group, you can also apply

the map_only attribute to a cell by using the set_map_only command.

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pad_cell Simple Attribute

In a cell group or a model group, the pad_cell attribute identifies a cell as a pad cell.

Syntax

pad_cell : true | false ;

If the pad_cell attribute is included in a cell definition (true), at least one pin in the cell

must have an is_pad attribute.

Example

pad_cell : true ;

If more than one pad cell can be used to build a logical pad, use the

auxiliary_pad_cell attribute in the cell definitions of all the component pad cells.

Syntax

auxiliary_pad_cell : true | false ;

Example

auxiliary_pad_cell : true ;

If the pad_cell or auxiliary_pad_cell attribute is omitted, the cell is treated as an

internal core cell rather than as a pad cell.

Note:

A cell with an auxiliary_pad_cell attribute can also be used as a core cell; a pull-up or

pull-down cell is an example of such a cell.

pad_type Simple Attribute

Use the pad_type attribute to identify a type of pad_cell or auxiliary_pad_cell that

requires special treatment.

Syntax

pad_type : value ;

Example

pad_type : clock;

power_cell_type Simple Attribute

Use the power_cell_type attribute to specify the cell type.

Syntax

power_cell_type : valueenum ;

value

Valid values are stdcell (standard cell) and macro (macro cell).

Example

power_cell_type : stdcell ;

power_gating_cell Simple Attribute

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Note:

The power_gating_cell attribute has been replaced by the

retention_cell attribute. See “retention_cell Simple Attribute” .

The cell-level power_gating_cell attribute specifies that a cell is a power gating cell. A

power gating cell has two modes. When functioning in normal mode, the power gating cell

functions as a regular cell. When functioning in power-saving mode, the power gating cell’s

power supply is shut off.

The pin-level map_to_logic attribute specifies which logic level the

power_gating_cell is tied to when the cell is functioning in normal mode.

Syntax

power_gating_cell : power_gating_cell_nameid ;

power_gating_cell_name

A string identifying the power gating cell name.

Example

power_gating_cell : "my_gating_cell" ;

preferred Simple Attribute

The preferred attribute with a true value indicates that the cell is the preferred

replacement during the gate-mapping phase of optimization.

Syntax

preferred : true | false ;

Example

preferred : true ;

This attribute can be applied to a cell with preferred timing or area attributes. For example,

in a set of 2-input NAND gates, you might want to use gates with higher drive strengths

wherever possible. This practice is useful primarily in design translation.

retention_cell Simple Attribute

The retention_cell attribute identifies a retention cell. The retention_cell_style

value is a random string.

Syntax

retention_cell : retention_cell_style ;

Example

retention_cell : my_retention_cell ;

scaling_factors Simple Attribute

Use the scaling_factors attribute to apply to a cell the scaling factor values defined in

the scaling_factors group at the library level.

Syntax

scaling_factors : group_nameid ;

group_name

Name of the set of special scaling factors in a scaling_factors

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85

statement at the library level.

Example 2-2 shows one of these special scaling factors in the library description and cell

description.

Example 2-2 Individual Scaling Factors

library (example) {

k_volt_intrinsic_rise : 0.987 ;

...

scaling_factors(IO_PAD_SCALING) {

k_volt_intrinsic_rise : 0.846 ;

...

}

cell (INPAD_WITH_HYSTERESIS) {

area : 0 ;

scaling_factors : IO_PAD_SCALING ;

...

}

...

}

Example 2-2 defines a scaling factor group called IO_PAD_SCALING that contains scaling

factors different from the library-level scaling factors. The scaling_factors attribute in

the INPAD_WITH_HYSTERESIS cell is set to IO_PAD_SCALING, so all scaling factors set

in the IO_PAD_SCALING group are applied to this cell.

sensitization_master Simple Attribute

The sensitization_master attribute defines the sensitization group referenced by the

cell to generate stimuli for characterization. The attribute is required if the cell contains

sensitization information. Its string value should be any sensitization group name

predefined in the current library.

Syntax

sensitization_master : sensitization_group_name;

sensitization_group_name

A string identifying the sensitization group name predefined in the current

library.

Example

sensitization_master : sensi_2in_1out;

single_bit_degenerate Simple Attribute

The single_bit_degenerate attribute names a single-bit library cell to link a multibit

black box cell with the single-bit version of the cell.

Syntax

single_bit_degenerate : "cell_nameid";

cell_name

A character string identifying a single-bit cell.

Example

cell (FDX2) {

area : 18 ;

single_bit_degenerate : "FDB" ;

/* FDB must be a single-bit cell in the library*/

bundle (D) {

members (D0, D1) ;

direction : input ;

...

timing ( ) {

...

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...

}

cell (FDX4) {

area : 32 ;

single_bit_degenerate : "FDB" ;

bus (D) {

bus_type : bus4 ;

direction : input ;

...

timing ( ) {

...

}

slew_type Simple Attribute

Use the slew_type attribute to specify the slew type for the output pins of the output or

the I/O cell.

Syntax

slew_type : "nameid ";

name

An alphanumeric string identifier, enclosed in quotation marks,

representing the slew type.

Example

slew_type : "slow" ;

switch_cell_type Simple Attribute

The switch_cell_type cell-level attribute provides a description of the switch cell so

that the switch cell does not need to be inferred through the other information specified in

the cell.

Syntax

switch_cell_type : coarse_grain ;

Example

switch_cell_type : coarse_grain ;

threshold_voltage_group Simple Attribute

The optional threshold_voltage_group attribute identifies a cell with a category,

based on the voltage characteristics of the cell.

Syntax

threshold_voltage_group : “group_nameid” ;

group_name

A string value representing the name of the category.

Example

cell () {

...

threshold_voltage_group : “high_vt_cell” ;

...

threshold_voltage_group : “low_vt_cell” ;

...

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}

timing_model_type Simple Attribute

Indicates not to infer transparent level-sensitive latch devices from timing arcs defined in

the cell. To indicate that transparent level-sensitive latches should be inferred for input pins,

use the tlatch group.

Syntax

timing_model_type : "nameid ";

name

Valid values are “abstracted”, “extracted”, and “qtm”.

Example

timing_model_type : "abstracted" ;

use_for_size_only Simple Attribute

You use this attribute to specify the criteria for sizing optimization. You set this attribute on

a cell at the library level.

Syntax

use_for_size_only : valueBoolean ;

value

Valid values are true and false.

Example

library(lib1){

cell(cell1){

area : 14 ;

use_for_size_only : true ;

pin(A){

...

}

...

}

vhdl_name Simple Attribute

In cell, model, and pin groups, this attribute resolves conflicts of invalid object names

when porting from .db to VHDL. Some .db object names might violate the more restrictive

VHDL rules for identifiers.

Note:

The report_lib -vhdl_name command produces a table of .db names and VHDL

name mapping.

Syntax

vhdl_name : "nameid" ;

name

A name to substitute for the pin name when you write out to VHDL.

Example

cell (INV) {

area : 1 ;

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pin(IN) {

vhdl_name : "INb" ;

direction : input ;

capacitance : 1 ;

}

pin(Z) {

direction : output ;

function : "IN’" ;

timing () {

intrinsic_rise : 0.23 ;

intrinsic_fall : 0.28 ;

rise_resistance : 0.13 ;

fall_resistance : 0.07 ;

related_pin : "IN" ;

}

2.1.3 Complex Attributes

This section lists, alphabetically, the complex attributes for the cell and model groups.

input_voltage_range Attribute

The input_voltage_range attribute specifies the allowed voltage range of the level-

shifter input pin and the voltage range for all input pins of the cell under all possible

operating conditions (defined across multiple libraries). The attribute defines two floating

values: the first is the lower bound, and second is the upper bound.

The input_voltage_range syntax differs from the pin-level

input_signal_level_low and input_signal_level_high syntax in the following

ways:

● The input_signal_level_low and input_signal_level_high attributes

are defined on the input pins under one operating condition.

● The input_signal_level_low and input_signal_level_high attributes

are used to specify the partial voltage swing of an input pin (that is, to prevent

from swinging from ground rail VSS to full power rail VDD). Note that

input_voltage_range is not related to the voltage swing.

Note:

The input_voltage_range and output_voltage_range attributes should

always be defined together.

Syntax

input_voltage_range (float, float) ;

Example

input_voltage_range (1.0, 2.0) ;

output_voltage_range Attribute

The output_voltage_range attribute is similar to the input_voltage_range attribute

except that it specifies the allowed voltage range of the level shifter for the output pin

instead of the input pin.

The output_voltage_range syntax differs from the pin-level

output_signal_level_low and output_signal_level_high syntax in the following

ways:

● The output_signal_level_low and output_signal_level_high

attributes are defined on the output pins under one operating condition.

● The output_signal_level_low and output_signal_level_high

attributes are used to specify the partial voltage swing of an output pin (that is, to

prevent from swinging from ground rail VSS to full power rail VDD). Note that

output_voltage_range is not related to the voltage swing.

Note:

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89

The input_voltage_range and output_voltage_range attributes should always be

defined together.

Syntax

output_voltage_range (float, float) ;

Example

output_voltage_range (1.0, 2.5) ;

pin_equal Complex Attribute

Use the pin_equal attribute to describe functionally equal (logically equivalent) groups of

input or output pins.

Syntax

pin_equal ("name_list") ;

name_list

A list of input or output pins whose values must be equal.

Example

In the following example, input pins IP1 and IP0 are logically equivalent.

pin_equal ("IP1 IP0") ;

pin_name_map Complex Attribute

The pin_name_map attribute defines the pin names that are used to generate stimuli from

the sensitization group for all timing arcs in the cell. The pin_name_map attribute is

optional when the pin names in the cell are the same as the the pin names in the

sensitization master, but it is required when they are different.

If the pin_name_map attribute is set, the number of pins must be the same as that in the

sensitization master, and all pin names should be legal pin names for the cell.

Syntax

pin_name_map (string…, string);

Example

pin_name_map (A, B, Z);

pin_opposite Complex Attribute

Use the pin_opposite attribute to describe functionally opposite (logically inverse)

groups of input or output pins.

Syntax

pin_opposite ("name_list1", "name_list2") ;

name_list1 , name_list2

A name_list of output pins requires the supplied output values to be

opposite. A name_list of input pins requires the supplied input values to

be opposite.

In the following example, pins IP and OP are logically inverse.

pin_opposite ("IP", "OP") ;

The pin_opposite attribute also incorporates the functionality of the pin_equal

complex attribute. In the following example, Q1, Q2, and Q3 are equal; QB1 and QB2 are

equal; and the pins in the first group are opposite of the pins in the second group.

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pin_opposite ("Q1 Q2 Q3", "QB1 QB2") ;

rail_connection Complex Attribute

Use the rail_connection attribute to specify the presence of multiple power supplies in

the cell. A cell with multiple power supplies contains two or more rail_connection

attributes.

Syntax

rail_connection (connection_nameid,power_supply_nameid) ;

connection_name

A string that specifies a power connection for the pin name.

power_supply_name

A string that specifies the power supply group already defined in the

power_supply group at the library level to be used as the value for

the power_level attribute in the internal_power group (defined in the

pin group).

Example

cell (IBUF1) {

...

rail_connection (PV1, VDD1) ;

rail_connection (PV2, VDD2) ;

...

}

resource_usage Complex Attribute

Use the resource_usage attribute to specify the name and the number of resources the

cell uses.

Syntax

resource_usage ( resource_nameid, number_of_resourcesint ) ;

resource_name

An alphanumeric identifier that matches the first argument in a max_count

attribute in the library. You can specify multiple resource_usage

attributes with different resource names.

number_of_resources

An integer representing the number of resources the cell uses.

Example

resource_usage (RES1, 1) ;

2.1.4 Group Statements

This section lists, alphabetically, the group statements for the cell and model groups.

cell Group Example

Example 2-3 shows cell definitions that include some of the CMOS cell attributes described

so far.

Example 2-3 cell Group Example

library (cell_example){

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91

date : "December 12, 2003" ;

revision : 2.3 ;

scaling_factors(IO_PAD_SCALING) {

k_volt_intrinsic_rise : 0.846 ;

}

cell (in){

vhdl_name : "inpad" ;

area : 0; /* pads do not normally consume

internal core area*/

cell_footprint : 5MIL ;

scaling_factors : IO_PAD_SCALING ;

pin (A) {

direction : input;

capacitance : 0;

}

pin (Z) {

direction : output;

function : "A";

timing () {...}

}

cell(inverter_med){

area : 3;

preferred : true;

/* tells Design Compiler to use this inverter first

during optimization */

pin (A) {

direction : input;

capacitance : 1.0;

}

pin (Z) {

direction : output;

function : "A’";

timing () { ...}

}

cell(and_nand){

area : 4;

pin_opposite("Y", "Z");

pin(A) {

direction : input

capacitance : 1

fanout_load : 1.0

}

pinup) {

direction : input

capacitance : 1

fanout_load : 1.0

}

pin (Y) {

direction : output

function : "(A * B)’"

timing() {...}

}

pin (Z){

direction : output

function : "(A * B)"

timing() {...}

}

cell(buff1){

area : 3;

pin_equal ("Y Z");

pin (A) {

direction : input;

capacitance : 1.0;

}

pin (Y) {

direction : output;

function : "A";

timing () {...}

}

pin (Z) {

direction : output;

function : "A";

timing () {...}

}

} /* End of Library */

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bundle Group

A bundle group uses the members complex attribute (unique to bundles) to group

together in multibit cells—such as quad latches and 4-bit registers—several pins that have

similar timing or functionality.

The bundle group contains the following three elements:

● The members complex attribute. It must be declared first in a bundle group.

● All simple attributes that also appear in a pin group.

● The pin group statement (including all the pin group simple and complex

attributes, and group statements).

Syntax

library (nameid) {

cell (nameid) {

geometry_print : string ;

single_bit_degenerate : string ;

bundle (string) {

members (string) ; /*Must be declared first*/

capacitance : float ;

...

pin (Z0) {

capacitance : float ;

...

timing () {

...

}

Note:

Bundle names, bundle elements, bundle members, members, and member pins are all

valid terms for pin names in a bundle group.

Simple Attributes

All pin group simple attributes are valid in a bundle group. Following are examples of

three simple attributes, which are described later in this section.

capacitance : float ;

direction : input | output | inout |internal ;

function : "Boolean" ;

Complex Attribute

members (nameid) ;

Group Statement

All pin group statements are valid in a bundle group.

pin (nameid | name_listid) { }

pin Attributes in a bundle Group

The pin group simple attributes in a bundle group define default attribute values for all

pins in that bundle group. The pin attributes can also appear in a pin group within the

bundle group.

capacitance Simple Attribute

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Use the capacitance attribute to define the load of an input, output, inout, or internal pin.

Syntax

capacitance : valuefloat ;

value

A floating-point number in units consistent with other capacitance

specifications throughout the library. Typical units of measure for

capacitance include picofarads and standardized loads.

The following example shows a bundle group that defines a capacitance attribute value

of 1 for input pins D0, D1, D2, and D3 in bundle D:

Example

bundle (D) {

members(D0, D1, D2, D3) ;

direction : input ;

capacitance : 1 ;

}

direction Simple Attribute

The direction attribute states the direction of member pins in a bundle group.

The direction listed for this attribute should be the same as that given for the pin in the

same bundle group (see the bundle Z pin in Example 2-4).

Syntax

direction : input | output | inout | internal ;

Example

In a bundle group, the direction of all pins must be the same. Example 2-4 shows two

bundle groups. The first group shows two pins (Z0 and Z1) whose direction is output. The

second group shows one pin (D0) whose direction is input.

Example 2-4 Direction of Pins in bundle Groups

cell(inv) {

area : 16 ;

cell_leakage_power : 8 ;

bundle(Z) {

members(Z0, Z1, Z2. Z3) ;

direction : output ;

function : "D" ;

pin(Z0) {

direction : output ;

timing() {

intrinsic_rise : 0.4 ;

intrinsic_fall : 0.4 ;

related_pin : "D0" ;

}

pin(Z1) {

direction : output ;

timing() {

intrinsic_rise : 0.4 ;

intrinsic_fall : 0.4 ;

related_pin : "D1" ;

}

bundle(D) {

members (D0, D1, D2, D3) ;

direction : input ;

capacitance : 1 ;

pin (D0 {

direction : input ;

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94

...

}

function Simple Attribute

The function attribute in a bundle group defines the value of an output pin or inout pin

in terms of the input pins or inout pins in the cell group or model group.

Syntax

function : "Boolean expression" ;

Table 2-4 lists the Boolean operators valid in a function statement.

Table 2-4 Valid Boolean Operators

Operator Description

' invert previous expression

! invert following expression

^ logical XOR

* logical AND

& logical AND

space logical AND

+ logical OR

| logical OR

1 signal tied to logic 1

0 signal tied to logic 0

The order of precedence of the operators is left to right, with inversion performed first, then

XOR, then AND, then OR.

Pin Names as Function Arguments

The following example describes bundle Q with the function A OR B:

bundle (Q) {

direction : output ;

function : "A + B" ;

}

A pin name beginning with a number must be enclosed in double quotation marks preceded

by a backslash (\), as in the following example.

function : " \"1A\" + \"1B\" " ;

The absence of a backslash causes the quotation marks to terminate the function string.

The following function statements all describe 2-input multiplexers. The parentheses are

optional. The operators and operands are separated by spaces.

function : "A S + B S’" ;

function : "A & S | B & !S" ;

function : "(A * S) + (B * S’)" ;

members Complex Attribute

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The members attribute lists the pin names of signals in a bundle. It provides the bundle

element names, and it groups a set of pins that have similar properties. It must be the first

attribute you declare in a bundle group.

Syntax

bundle (namestring) {

members (member1, member2 ... ) ;

...

}

member1 , member2 ...

The number of bundle members defines the width of the bundle.

Example

members (D1, D2, D3, D4) ;

If the function attribute has been defined for the bundle, the function value is copied

to all bundle members.

Example

bundle(A) {

members(A0, A1, A2, A3);

direction : output ;

function : "B’+ C";

...

}

bundle(B) {

members(B0, B1, B2, B3);

direction : input;

...

}

The previous example shows that the members of the A bundle have these values:

A0 = B0’ + C ;

A1 = B1’ + C ;

A2 = B2’ + C ;

A3 = B3’ + C ;

Each bundle operand (B) must have the same width as the function parent bundle (A).

Example 2-5 shows how to define a bundle group in a cell with a multibit latch.

Example 2-5 Multibit Latch With Signal Bundles

cell (latch4) {

area: 16 ;

geometry_print : GP1;

pin (G) { /* active-high gate enable signal */

direction : input ;

...

}

bundle (D){ /* data input with four member

pins */

members (D1, D2, D3, D4) ; /*must be first

attribute */

direction : input ;

}

bundle (Q) {

members (Q1, Q2, Q3, Q4) ;

direction : output ;

function : "IQ" ;

}

bundle (QN) {

members (Q1N, Q2N, Q3N, Q4N) ;

direction : output ;

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function : "IQN" ;

}

latch_bank(IQ, IQN, 4) {

enable : "G" ;

data_in : "D" ;

}

pin Group Statement in a bundle Group

You can define attribute values for specific pins or groups of pins in a pin group within a

bundle group. Values in a pin group override the default attribute values defined for the

bundle (described previously).

Syntax

bundle(namestring) {

pin (namestring) {

... pin description ...

}

The following example shows a pin group in a bundle group that defines a new

capacitance attribute value for member A0 in bundle A:

Example

bundle (A) {

pin (A0) {

capacitance : 4 ;

}

To identify the name of a pin in a pin group within a bundle group, use the full name of a

pin, such as pin (A0) in the previous example.

All pin names within a single bundle group must be unique. Pin names are case-sensitive;

for example, pins named A and a are different pins.

Example 2-4 shows a pin group within a bundle group.

bus Group

A bus group, defined in a cell group or a model group, defines the bused pins in the

library. Before you can define a bus group you must first define a type group at the library

level.

From the type group you define at the library level, use the type name (bus4 in Example 2-

6) as the value for the bus_type attribute in the bus group in the same library.

Example 2-6 a bus group in a cell group.

Example 2-6 Bused Pins

library (ExamBus) {

type (bus4) { /* bus name */

bit_width : 4 ; /* number of bused pins */

...

}

cell (bused cell) {

...

bus (A) {

bus_type : bus4 ; /* bus name */

...

}

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Simple Attributes

You can use all of the pin simple attributes in bus group, plus the following attribute.

bus_type : name ;

Group Statement

pin (namestring | name_liststring) { }

All group statements that appear in a pin group are valid in a bus group.

bus_type Simple Attribute

The bus_type attribute is a required element of all bus groups. The attribute defines the

type of bus. It must be the first attribute declared in a bus group.

Syntax

bus_type : name ;

name

Define this name in the applicable type group in the library, as shown in

Example 2-6.

pin Simple Attributes in a bus Group

The pin simple attributes in a bus group define default attribute values for all pins in the

bus group.

Note:

Bus names, bus members, bus pins, bused pins, pins, members, member numbers, and

range of bus members are valid terms for pin names in a bus group.

All pin group simple attributes are valid within a bus group and within a pin group in a

bus group.

The capacitance and direction attributes are frequently used in bus groups.

capacitance Simple Attribute

Use the capacitance attribute to define the load of an input, output, inout, or internal pin.

Syntax

capacitance : valuefloat ;

value

A floating-point number in units consistent with other capacitance

specifications throughout the library. Typical units of measure for

capacitance include picofarads and standardized loads.

The following example shows a bus group that defines bus A with default values assigned

for direction and capacitance.

Example

bus (A) {

bus_type : bus1 ;

direction : input ;

capacitance : 3 ;

}

direction Simple Attribute

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The direction attribute states the direction of bus members (pins) in a bus group.

The value of the direction attribute of all bus members (pins) in a bus group must be

the same. (To see a bus group with more than one pin, refer to Example 2-7.)

Syntax

direction : input | output | inout | internal ;

Example

direction : inout ;

pin Group Statement in a bus Group

This group defines attribute values for specific bused pins or groups of bused pins in a pin

group within a bus group. Values used in a pin group within a bus group override the

defined default bus pin attribute values described previously.

Note:

You can use a defined bus or buses in Boolean expressions in the function attribute of a

pin in a bus group, as shown in Example 2-7.

The following example shows a bus pin group that defines a new capacitance attribute

value for member AO in bus A.

bus(A) {

pin (AO) {

capacitance : 4 ;

}

To identify the name of a bused pin in a pin group within a bus group, use the full name of

the pin.You can identify bus member numbers as single numbers or as a range of numbers

separated by a colon. No spaces can appear between the colon and the member numbers.

Example

pin (A[O:2]) {}

The next example shows a pin group within a bus group that defines a new

capacitance attribute value for a single pin number.

bus(A) {

pin (A) {

capacitance : 4 ;

}

The next example shows a pin group within a bus group that defines a new

capacitance attribute value for bus members 0, 1, 2, and 3 in bus A.

bus(A) {

pin (A[0:3]) {

capacitance : 4 ;

}

Sample Bus Description–Technology Library

Example 2-7 illustrates a complete bus description that includes a library-defined type

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group and cell-defined bus groups. The example also illustrates the use of bus variables in

a function attribute in a pin group and in a related_pin attribute in a timing group.

Example 2-7 Bus Description

library (ExamBus) {

date : "November 12, 2000" ;

revision : 2.3 ;

bus_naming_style :"%s[%d]" ;

/* Optional; this is the default */

type (bus4) {

base_type : array ;/* Required */

data_type : bit ;/* Required if base_type is array */

bit_width : 4 ;/* Optional; default is 1 */

bit_from : 0 ;/* Optional MSB; defaults to 0 */

bit_to : 3 ;/* Optional LSB; defaults to 0 */

downto : false ;/* Optional; defaults to false */

}

cell (bused_cell) {

area : 10 ;

geometry_print : GP1 ;

single_bit_degenerate : FDB ;

bus (A) {

bus_type : bus4 ;

direction : input ;

capacitance : 3 ;

pin (A[0:2]) {

capacitance : 2 ;

}

pin (A[3]) {

capacitance : 2.5 ;

}

bus (B) {

bus_type : bus4 ;

direction : input ;

capacitance : 2 ;

}

bus (E) {

direction : input ;

capacitance 2 ;

}

bus(X) {

bus_type : bus4 ;

direction : output ;

capacitance : 1 ;

pin (X[0:3]) {

function : "A & B’" ;

timing() {

related_pin : "A B" ;

/* A[0] and B[0] are related to X[0],

A[1] and B[1] are related to X[1], etc. */

}

bus (Y) {

bus_type : bus4 ;

direction : output ;

capacitance : 1 ;

pin (Y[0:3]) {

function : "B" ;

three_state : "!E" ;

timing () {

related_pin : "A[0:3] B E" ;

}

bus (Z) {

bus_type : bus4 ;

direction : output ;

pin (Z[0:1]) {

function : "!A[0:1]" ;

timing () {

related_pin : "A[0:1]" ;

}

pin (Z[2]) {

function "A[2]" ;

timing () {

related_pin : "A[2]" ;

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}

pin (Z[3]) {

function : "!A[3]" ;

timing () {

related_pin : "A[3]" ;

}

dynamic_current Group

Use the dynamic_current group to specify a current waveform vector when the power and

ground current is dependent on the logical condition of a cell. A dynamic_current group

is defined in a cell group, as shown here:

library (name) {

cell (name) {

dynamic_current () {

when : <boolean expression>

related_inputs : <input_pin_name>;

related_outputs : <output_pin_name>;

typical_capacitances("<float>, …");

switching_group() {

input_switching_condition(<enum(rise, fall)>);

output_switching_condition(<enum(rise, fall)>);

pg_current(<pg_pin_name>) {

vector(<template_name>) {

reference_time : <float>;

index_output : <output_pin_name>;

index_1(<float>);

…

index_n(<float>);

index_n+1("<float>, …");

values("<float>, …");

} /* vector */

…

} /pg_current */

…

} /* switching_group */

…

} /* dynamic_current */

…

} /* cell */

Simple Attributes

related_inputs

related_outputs

typical_capacitances

when

Group Statement

switching_group

related_inputs Simple Attribute

This attribute defines the input condition of input pins. If only one input is switching during

the time period, the input condition is defined as “single input event.” If more than one input

pin is switching, the input condition is defined as “multiple input events.”

● This attribute is required.

● A list of input pins can be specified in the attribute.

● Because “single input event” is supported, exactly one of the input pins in the list

must be toggling to match input condition.

● “Multiple input events” are not supported.

● The pins in the list can be in any order.

● Bus and bundle are supported.

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Syntax

related_inputs : <input_pin_name>;

input_pin_name

Name of input pin.

Example

related_inputs : A ;

related_outputs Simple Attribute

The related_outputs attribute defines the output condition of specified output pins. If no

toggling output occurs as a trigger event is given, the condition is called a “non-propagating

event.” If an event propagates through the cell and causes at least one output toggling,

then it is called a “propagating event.”

● This attribute is optional.

● A list of output pins can be specified in the attribute.A “single input event”

matches the output condition for all toggling output pins in the list. The pins in

the list can be in any order.Bus and bundle are supported only in bit level. For a

standard cell, if the attribute is specified, it represents a “propagating event.”

Otherwise, if it is missing, it represents a “non-propagating event.”There is no

related_outputs attribute for macro cells. Therefore, you do not need to

distinguish between non-propagating and propagating event tables.

Syntax

related_outputs : <output_pin_name> ;

name

Name of output pin.

Example

related_outputs : D ;

typical_capacitances Simple Attribute

The typical_capacitances attribute defines fixed capacitance values for all output pins

specified in related_outputs.The order in the list of this attribute is mapped to the same

order of output pins in the related_outputs attribute. For example :

…

/* the fixed capacitance of Q1 is 10.0, Q2 is 20.0, and Q3

is 30.0. */

related_outputs : "Q1 Q2 Q3";

typical_capacitances(10.0 20.0 30.0);

…

The attribute is required for cross type. If data in the vector group is not defined as a sparse

cross table, the specified values in the attribute will be ignored.

Syntax

typical_capacitances ("<float>, …");

float

Value of capacitance on pin.

Example

typical_capacitances (10.0 20.0);

when Simple Attribute

Use the when attribute to specify a state-dependent condition that determines whether the

instantaneous power data can be accessed.

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Syntax

when : <boolean expression>

boolean expression

Expression determines whether the instantaneous power data is accessed.

switching_group Group

Use the switching_group group to specify a current waveform vector when the power and

ground current is dependent on pin switching conditions.

library (name) {

cell (name) {

dynamic_current () {

...

switching_group() {

... switching_group description...

}

Simple Attributes

input_switching_condition

output_switching_condition

min_input_switching_count

max_input_switching_count

Group

pg_current

input_switching_condition Simple Attribute

Use the input_switching_condition attribute to specify the sense of the toggling

input. If there is more than one switching_group group specified within the

dynamic_current group, you can place the attribute in any order. The order in the list of

the output_switching_condition attribute is mapped to the same order of output pins

in the related_outputs attribute.Two values are allowed: rise represents a rising pin

and can be applied for input/output switching conditions and fall represents a falling pin

and can be applied for input/output switching conditions.

Syntax

input_switching_condition (<enum(rise, fall)>);

enum(rise, fall)

Enumerated type specifing rise or fall condition.

Example

input_switching_condition (rise);

output_switching_condition Simple Attribute

Use the output_switching_condition attribute to specify the sense of the toggling

output. If there is more than one switching_group group specified within the

dynamic_current group, you can place the attribute in any order. The order in the list of

the output_switching_condition attribute is mapped to the same order of output pins

in the related_outputs attribute.Currently, two values are considered: rise represents

a rising pin and can be applied for input/output switching conditions and fall represents a

falling pin and can be applied for input/output switching conditions.

Syntax

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output_switching_condition (<enum(rise, fall)>);

enum(rise, fall)

Enumerated type specifing rise or fall condition.

Example

output_switching_condition (rise, fall);

min_input_switching_count Simple Attribute

The min_input_switching_count attribute specifies the minimum number of bits in the

input bus that are switching simultaneously. The following applies to the

min_input_switching_count attribute:

● The count must be an integer.

● The count must be greater than 0 and less than the

max_input_switching_count value.

Syntax

switching_group() {

min_input_switching_count : integer ;

max_input_switching_count : integer ;

...

}

Example

switching_group() {

min_input_switching_count : 1 ;

max_input_switching_count : 3 ;

...

}

max_input_switching_count Attribute

The max_input_switching_count attribute specifies the maximum number of bits in

the input bus that are switching simultaneously. The following applies to the

max_input_switching_count attribute:

● The count must be an integer.

● The count must be greater than the min_input_switching_count value.

● The count within a dynamic_current should cover the total number of input

bits specified in related_inputs.

Syntax

switching_group() {

min_input_switching_count : integer ;

max_input_switching_count : integer ;

...

}

Example

switching_group() {

min_input_switching_count : 1 ;

max_input_switching_count : 3 ;

...

}

pg_current Group

Use the pg_current group to specify current waveform data in a vector group. If all

vectors under the group are dense, data in this group is represented as a dense table. If all

vectors under the group are sparse in cross type, data in this group is represented as a

sparse cross table. If all vectors under the group are sparse in diagonal type, data in this

group is represented as a sparse diagonal table.

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library (name) {

cell (name) {

dynamic_current () {

...

switching_group() {

...

pg_current () {}

... pg current description ...

}

Group

vector

vector Group

Use the vector group to specify the current waveform for a power and ground pin. This

group represents a single current waveform based on specified input slew and output load.

● Data in this group is represented as a dense table, if a template with two

total_output_net_capacitance variables is applied to the group. If a

dense table is applied, the order of total_output_net_capacitance

variables must map to the order of values in the related_outputs attribute.

● Data in this group is represented as a sparse cross table, if the index_output

attribute is defined in the group.

● Data in this group is represented as a sparse diagonal table, if no

index_output attribute is defined in the group and a template with exact one

total_output_net_capacitance variable is applied to the group.

library (name) {

cell (name) {

dynamic_current () {

switching_group() {

pg_current () {}

vector () {

... vector description ...

}

Simple Attributes

index_1 (<float>);

index_2 (<float>);

index_3 (<float>);

index_4 (<float>);

index_output : <output_pin_name>;

reference_time:<float>;

values ("<float>, …");

index_1, index_, index_3, and index_4 Simple Attributes

The index attributes specify values for variables specified in the pg_current_template.

The index value for input_net_transition or total_output_net_capacitance is

a single floating-point number. You create a list of floating-point numbers for the index

values for time. Note the following:

● Different numbers of points are allowed for each waveform.

● If no output or only one output is specified in related_outputs, the table must

be dense.

● If two outputs are specified in related_outputs, the table can be either dense

or sparse.

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● If more than two outputs are specified, the table must be sparse.

● For a cross-type sparse table, a fixed capacitance of all outputs must be

specified in typical_capacitances. The sweeping output must be specified

in index_output, and the varied capacitance of that output must be specified

in one of the index attributes. The specified index attribute must map to the

total_output_net_capacitance variable in the template.

● For a diagonal-type sparse table, capacitances of all outputs are identical and

they can be specified in one of the index attributes. The specified index must

map to the total_output_net_capacitance variable in the template.

index_output Simple Attribute

This attribute specifies which output capacitance is sweeping while the others are held as

fixed values. This attribute is required for cross type. The attribute cannot be defined if the

vector table is not defined as a sparse cross table.

Syntax

index_output : <output_pin_name>;

output_pin_name

Name of the pin that the output capacitance is sweeping.

Example

index_output : “QN”;

reference_time Simple Attribute

This attribute represents the time at which the input waveform crosses the reference

voltage.

Syntax

reference_time : <float>;

float

Specifies the time at which the input waveform crosses the reference

voltage.

Example

reference_time : 0.01;

values Simple Attribute

The values attribute defines a list of floating-point numbers that represent the dynamic

current waveform of a specified power and ground pin.

Syntax

values:("<float>, …");

float

Defines a list of floating-point numbers that represent the dynamic current

waveform of a specified power and ground pin.

Example

values : ("0.002, 0.009, 0.134, 0.546");

ff Group

The ff group describes either a single-stage or a master-slave flip-flop in a cell or test cell.

The syntax for a cell is shown here. For information about the test_cell group, see

“test_cell Group ” .

Syntax

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library (namestring) {

cell (namestring) {

ff (variable1string, variable2string) {

... flip-flop description ...

}

The variable1 value is the state of the noninverting output of the flip-flop; the

variable2 value is the state of the inverting output. The variable1 value can be

considered the 1-bit storage of the flip-flop. Valid values for variable1 and variable2

are anything except a pin name used in the cell being described. Both of these variables

must be assigned, even if one of them is not connected to a primary output pin.

Simple Attributes

clear : "Boolean expression" ;

clear_preset_var1 : L | H | N | T | X ;

clear_preset_var2 : L | H | N | T | X ;

clocked_on : "Boolean expression" ;

clocked_on_also : "Boolean expression" ;

next_state : "Boolean expression" ;

preset : "Boolean expression" ;

clear Simple Attribute

The clear attribute gives the active value for the clear input.

Syntax

clear : "Boolean expression" ;

Example

clear : "CD’" ;

“Single-Stage Flip-Flop ” contains more information about the clear attribute.

clear_preset_var1 Simple Attribute

The clear_preset_var1 attribute gives the value that variable1 has when clear and

preset are both active at the same time.

Syntax

clear_preset_var1 : L | H | N | T | X ;

Example

clear_preset_var1 : H ;

Table 2-5 shows the valid variable values for the clear_preset_var1 simple attribute.

Table 2-5 Valid Values for the clear_preset_var1 and clear_preset_var2 Attributes

Variable values Equivalence

L 0

H 1

N No change1

T Toggle the current value from 1 to 0, 0 to 1, or X to X1

X Unknown1

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1 Use these values to generate VHDL models.

“Single-Stage Flip-Flop ” contains more information about the clear_preset_var1

attribute, including its function and values.

clear_preset_var2 Simple Attribute

The clear_preset_var2 attribute gives the value that variable2 has when clear and

preset are both active at the same time.

Syntax

clear_preset_var2 : L | H | N | T | X ;

Example

clear_preset_var2 : L ;

“Single-Stage Flip-Flop ” contains more information about the clear_preset_var2

attribute, including its function and values.

clocked_on and clocked_on_also Simple Attributes

The clocked_on and clocked_on_also attributes identify the active edge of the clock

signals and are required in all ff groups. For example, use clocked_on : "CP" to

describe a rising-edge-triggered device and use clocked_on_also : "CP" for a falling-

edge-triggered device.

Note:

A single-stage flip-flop does not use clocked_on_also. See “Single-Stage Flip-Flop ” for

details.

When describing flip-flops that require both a master clock and a slave clock, use the

clocked_on attribute for the master clock and the clocked_on_also attribute for the

slave clock.

Syntax

clocked_on : "Boolean expression" ;

clocked_on_also : "Boolean expression" ;

Boolean expression

Active edge of a clock signal.

Example

clocked_on : "CP" ;

clocked_on_also : "CP’" ;

next_state Simple Attribute

Required in all ff groups, next_state is a logic equation written in terms of the cell’s

input pins or the first state variable, variable1. For single-stage storage elements, the

next_state attribute equation determines the value of variable1 at the next active

transition of the clocked_on attribute.

For devices such as a master-slave flip-flop, the next_state equation determines the

value of the master stage’s output signals at the next active transition of the clocked_on

attribute.

The type of pin that appears in the Boolean expression of a next_state attribute is

defined in a pin group with the nextstate_type attribute.

Syntax

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next_state : "Boolean expression" ;

The following example shows an ff group for a single-stage D flip-flop.

ff (IQ, IQN) {

next_state : "D" ;

clocked_on : "CP" ;

}

The example defines two variables, IQ and IQN. The next_state equation determines

the value of IQ after the next active transition of the clocked_on attribute. In this example,

IQ is assigned the value of the D input.

In some flip-flops, the next state depends on the current state. In this case, the first state

variable (IQ in the example) can be used in the next_state statement; the second state

variable, IQN, cannot.

For example, the ff declaration for a JK flip-flop looks like this:

ff(IQ,IQN) {

next_state : "(J K IQ’) + (J K’) + (J’ K’ IQ)" ;

clocked_on : "CP" ;

}

The next_state and clocked_on attributes completely define the synchronous behavior

of the flip-flop.

preset Simple Attribute

The preset attribute gives the active value for the preset input.

Syntax

preset : "Boolean expression" ;

Example

preset : "PD’" ;

Single-Stage Flip-Flop

A single-stage flip-flop does not use the optional clocked_on_also attribute.

The clear attribute gives the active value for the clear input. The preset attribute gives

the active value for the preset input. For example, the following statement defines an active-

low clear signal:

clear : "CD’" ;

Table 2-6 shows the functions of the attributes in the ff group for a single-stage flip-flop.

Table 2-6 Function Table for a Single-Stage Flip-Flop

clocked_on clear preset variable1 variable2

active edge

inactive

next_state !next_state

-- active inactive

0 1

-- inactive

active 1 0

-- active active clear_preset_var1

clear_preset_var2

The clear_preset_var1 and clear_preset_var2 attributes give the value that

variable1 and variable2 have when clear and preset are both active at the same

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time. See Table 2-6 for the valid variable values.

If the clear and preset attributes are both included in the group, either

clear_preset_var1, clear_preset_var2, or both must be defined. Conversely, if

either clear_preset_var1, or clear_preset_var2, or both are included, both

clear and preset must be defined.

The flip-flop cell is activated whenever the value of clear, preset, clocked_on, or

clocked_on_also changes.

Example 2-8 is an ff group for a single-stage D flip-flop with rising-edge sampling,

negative clear and preset, and output pins set to 0 when both clear and preset are active

(low).

Example 2-8 Single-Stage D Flip-Flop

ff(IQ, IQN) {

next_state : "D" ;

clocked_on : "CP" ;

clear : "CD’" ;

preset : "PD’" ;

clear_preset_var1 : L ;

clear_preset_var2 : L ;

}

Example 2-9 is an ff group for a single-stage, rising-edge-triggered JK flip-flop with scan

input, negative clear and preset, and output pins set to 0 when clear and preset are both

active.

Example 2-9 Single-Stage JK Flip-Flop

ff(IQ, IQN) {

next_state :

"(TE*TI)+(TE’*J*K’)+(TE’*J’*K’*IQ)+(TE’*J*K*IQ’)" ;

clocked_on : "CP" ;

clear : "CD’" ;

preset : "PD’" ;

clear_preset_var1 : L ;

clear_preset_var2 : L ;

Example 2-10 is an ff group for a D flip-flop with synchronous negative clear.

Example 2-10 D Flip-Flop With Synchronous Negative Clear

ff (IQ, IQN) {

next_state : "D * CLR’" ;

clocked_on : "CP" ;

}

Master-Slave Flip-Flop

The syntax for a master-slave flip-flop is the same as for a single-stage device, except that

it includes the clocked_on_also attribute. Table 2-7 shows the functions of the attributes

in the ff group for a master-slave flip-flop.

The internal1 and internal2 variables represent the output values of the master

stage, and variable1 and variable2 represent the output values of the slave stage.

The variable1 and variable2 variables have the same value as internal1 and

internal2, respectively, when clear and preset are both active at the same time.

Table 2-7 Function Table for a Master-Slave Flip-Flop

Variable Functions

clear active active inactive

inactive inactive

preset active inactive

active inactive inactive

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internal1 clear_preset_var1

0 1 next_state

internal2 clear_preset_var2

1 0 !next_state

variable1 clear_preset_var1

0 1 internal1

variable2 clear_preset_var2

1 0 internal2

active edge

clocked_on

clocked_on_also

Example 2-11 shows an ff group for a master-slave D flip-flop with rising-edge sampling,

falling-edge data transfer, negative clear and preset, and output values set high when clear

and preset are both active.

Example 2-11 Master-Slave D Flip-Flop

ff(IQ, IQN) {

next_state : "D" ;

clocked_on : "CLK" ;

clocked_on_also : "CLKN’" ;

clear : "CDN’" ;

preset : "PDN’" ;

clear_preset_var1 : H ;

clear_preset_var2 : H ;

}

ff_bank Group

An ff_bank group is defined within a cell or test_cell group, as shown in the

following syntax, and in a scaled_cell group at the library level.

The ff_bank group describes a cell that is a collection of parallel, single-bit sequential

parts. Each part can share control signals with the other parts and performs an identical

function. The ff_bank group is typically used to represent multibit registers in cell and

test_cell groups. For information about ff_bank in test cells, see “test_cell Group ” .

The syntax for the ff_bank group is similar to that of the ff group.

Syntax

library (namestring) {

cell (namestring) {

ff_bank (variable1string, variable2string,

bitsinteger) {

... multibit flip-flop register description ...

}

Simple Attributes

clocked_on : "Boolean expression" ;

next_state : "Boolean expression" ;

clear : "Boolean expression" ;

preset : "Boolean expression" ;

clear_preset_var1 : L | H | N | T | X ;

clear_preset_var2 : L | H | N | T | X ;

clocked_on_also : "Boolean expression" ;

Example 2-12 shows an ff_bank group for a multibit D flip-flop.

An input described in a pin group, such as the clk input, is fanned out to each flip-flop in

the bank. Each primary output must be described in a bus or bundle group, whose

function statement must include either variable1 or variable2.

clocked_on and clocked_on_also Simple Attributes

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Required in all ff_bank groups, the clocked_on and clocked_on_also attributes

identify the active edge of the clock signal.

When describing flip-flops that require both a master and a slave clock, use the

clocked_on attribute for the master clock and the clocked_on_also attribute for the

slave clock.

Syntax

clocked_on : "Boolean expression" ;

clocked_on_also : "Boolean expression" ;

Boolean expression

Active edge of the edge-triggered device.

Examples

clocked_on : "CP" ; /* rising-edge-triggered device */

clocked_on_also : "CP’"; /* falling-edge-triggered device */

next_state Simple Attribute

Required in all ff_bank groups, the next_state attribute is a logic equation written in

terms of the cell’s input pins or the first state variable, variable1. For single-stage flip-

flops, the next_state attribute equation determines the value of variable1 at the next

active transition of the clocked_on attribute.

For devices such as master-slave flip-flops, the next_state equation determines the

value of the master stage’s output signals at the next active transition of the clocked_on

attribute.

Syntax

next_state : "Boolean expression" ;

Boolean expression

Identifies the active edge of the clock signal.

Example

next_state : "D" ;

The type of a next_state attribute is defined in a pin group with the nextstate_type

attribute.

clear Simple Attribute

The clear attribute gives the active value for the clear input.

Syntax

clear : "Boolean expression" ;

Example

clear : "CD’" ;

See “Single-Stage Flip-Flop ” for more information about the clear attribute.

preset Simple Attribute

The preset attribute gives the active value for the preset input.

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Syntax

preset : "Boolean expression" ;

Example

preset : "PD’" ;

See “Single-Stage Flip-Flop ” for more information about the preset attribute.

clear_preset_var1 Simple Attribute

The clear_preset_var1 attribute gives the value that variable1 has when clear and

preset are both active at the same time.

Table 2-8 shows the valid variable values for the clear_preset_var1 and

clear_preset_var2 attributes.

Table 2-8 Valid Values for the clear_preset_var1 and clear_preset_var2 Attributes

Variable values Equivalence

L 0

H 1

N No change1

T Toggle the current value from 1 to 0, 0 to 1, or X to X1

X Unknown1

1 Use these values to generate VHDL models.

Syntax

clear_preset_var1 : L | H | N | T | X ;

Table 2-8 shows the valid variable values for the clear_preset_var2 attribute.

Example

clear_preset_var1 : L ;

See “Single-Stage Flip-Flop ” for more information about the clear_preset_var1

attribute, including its function and values.

clear_preset_var2 Simple Attribute

The clear_preset_var2 attribute gives the value that variable2 has when clear and

preset are both active at the same time.

Syntax

clear_preset_var2 : L | H | N | T | X ;

Example

clear_preset_var2 : L ;

See “Single-Stage Flip-Flop ” for more information about the clear_preset_var1

attribute, including its function and values.

Multibit Flip-Flop

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The bits value in the ff_bank definition is the number of bits in this multibit cell.

Syntax

library (namestring) {

cell (namestring) {

ff_bank (variable1string, variable2string,

bitsinteger) {

... multibit flip-flop register description ...

}

A multibit register containing four rising-edge-triggered D flip-flops with clear and preset

is shown in Figure 2-1 and Example 2-12.

Figure 2-1 Multibit Register

Example 2-12 Multibit Register

cell (dff4) {

area : 1 ;

pin (CLK) {

direction : input ;

capacitance : 0 ;

min_pulse_width_low : 3 ;

min_pulse_width_high : 3 ;

}

bundle (D) {

members(D1, D2, D3, D4);

nextstate_type : data;

direction : input ;

capacitance : 0 ;

timing() {

related_pin : "CLK" ;

timing_type : setup_rising ;

intrinsic_rise : 1.0 ;

intrinsic_fall : 1.0 ;

}

timing() {

related_pin : "CLK" ;

timing_type : hold_rising ;

intrinsic_rise : 1.0 ;

intrinsic_fall : 1.0 ;

}

pin (CLR) {

direction : input ;

capacitance : 0 ;

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timing() {

related_pin : "CLK" ;

timing_type : recovery_rising ;

intrinsic_rise : 1.0 ;

intrinsic_fall : 0.0 ;

}

pin (PRE) {

direction : input ;

capacitance : 0 ;

timing() {

related_pin : "CLK" ;

timing_type : recovery_rising ;

intrinsic_rise : 1.0 ;

intrinsic_fall : 0.0 ;

}

ff_bank (IQ, IQN, 4) {

next_state : "D" ;

clocked_on : "CLK" ;

clear : "CLR’" ;

preset : "PRE’" ;

clear_preset_var1 : L ;

clear_preset_var2 : L ;

}

bundle (Q) {

members(Q1, Q2, Q3, Q4);

direction : output ;

function : "(IQ)" ;

timing() {

related_pin : "CLK" ;

timing_type : rising_edge ;

intrinsic_rise : 2.0 ;

intrinsic_fall : 2.0 ;

}

timing() {

related_pin : "PRE" ;

timing_type : preset ;

timing_sense : negative_unate ;

intrinsic_rise : 1.0 ;

}

timing() {

related_pin : "CLR" ;

timing_type : clear ;

timing_sense : positive_unate ;

intrinsic_fall : 1.0 ;

}

bundle (QN) {

members(Q1N, Q2N, Q3N, Q4N);

direction : output ;

function : "IQN" ;

timing() {

related_pin : "CLK" ;

timing_type : rising_edge ;

intrinsic_rise : 2.0 ;

intrinsic_fall : 2.0 ;

}

timing() {

related_pin : "PRE" ;

timing_type : clear ;

timing_sense : positive_unate ;

intrinsic_fall : 1.0 ;

}

timing() {

related_pin : "CLR" ;

timing_type : preset ;

timing_sense : negative_unate ;

intrinsic_rise : 1.0 ;

}

} /* end of cell dff4 */

fpga_condition Group

An fpga_condition group declares an fpga_condition group containing several

fpga_condition_value groups.

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Syntax

cell (nameid) {

fpga_condition (nameid) {

...

}

name

Specifies the name of the fpga_condition group.

Group

fpga_condition_value

fpga_condition_value Group

The fpga_condition_value group specifies a condition.

Syntax

cell (nameid) {

fpga_condition (condition_group_nameid) {

fpga_condition_value (condition_nameid){

...

}

condition_name

Specifies the name of a condition.

Simple Attribute

fpga_arc_condition

fpga_arc_condition Simple Attribute

The fpga_arc_condition attribute specifies a Boolean condition that enables the

associated fpga_condition_value group.

Syntax

cell (namestring) {

fpga_condition (nameid) {

fpga_condition_value (condition_nameid){

fpga_arc_condition : conditionBoolean ;

}

condition

Specifies a Boolean condition. Valid values are true and false.

Example

fpga_arc_condition : true ;

functional_yield_metric Group

To model yield information, use the functional_yield_metric group with the

faults_lut_template group. For details on the faults_lut_template group, see

“faults_lut_template” .

Syntax

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functional_yield_metric () {

average_number_of_faults ( namefaults_lut_template ) {

values ( "float, ..., float" );

}

This group holds values for average_number_of_faults. The group name indicates

that its values array is based on the specified faults_lut_template template.The

average_number_of_faults group holds the array of fault values.

Example

library ( my_library_name ) {

…

faults_lut_template ( my_faults_temp ) {

variable_1 : fab_name;

variable_2 : time_range;

index_1 ( " fab1, fab2, fab3 ");

index_2 (" 2005.01, 2005.07, 2006.01, 2006.07 ");

}

…

cell ( and2 ) {

…

functional_yield_metric () {

average_number_of_faults ( my_faults_temp ) {

values ( " 73.5, 78.8, 85.0, 92 ",\

" 74.3, 78.7, 84.8, 92.2 ",\

" 72.2, 78.1, 84.3, 91.0 " );

}

…

} /* end of cell */

} /* end of library */

This example specifies fault data for three fabs (fab1, fab2, and fab3).

For fab1:

● 73.5 is the average number of faults due to functional yield loss mechanisms

(that is, random defects) for the time range 2005.01 to 2005.06

● 78.8 is the average number of faults due to functional yield loss mechanisms for

the time range 2005.07 to 2005.12

● 85.0 is the average number of faults due to functional yield loss mechanisms for

the time range 2006.01 to 2006.07

● 92.0 is the average number of faults due to functional yield loss mechanisms for

the time range 2006.07 or later

For fab2:

● 74.3 is the average number of faults due to functional yield loss mechanisms for

the time range 2005.01 to 2005.06

● 78.7 is the average number of faults due to functional yield loss mechanisms for

the time range 2005.07 to 2005.12

● 84.8 is the average number of faults due to functional yield loss mechanisms for

the time range 2006.01 to 2006.07

● 92.2 is the average number of faults due to functional yield loss mechanisms for

the time range 2006.07 or later

And so on for fab3.

generated_clock Group

A generated_clock group is defined within a cell group or a model group to describe

a new clock that is generated from a master clock by

● Clock frequency division

● Clock frequency multiplication

● Edge derivation

Syntax

cell (namestring) {

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generated_clock (namestring) {

...clock data...

}

Simple Attributes

clock_pin : "name1 [name2 name3 ... ]" ;

master_pin : name ;

divided_by : integer ;

multipled_by : integer ;

invert : Boolean ;

duty_cycle : float ;

Complex Attributes

edges

shifts

clock_pin Simple Attribute

The clock_pin attribute identifies a pin connected to a master clock signal.

Syntax

clock_pin : "name1 [name2 name3 ... ]" ;

Example

clock_pin : "clk1 clk2 clk3" ;

master_pin Simple Attribute

The master_pin attribute identifies a pin connected to an input clock signal.

Syntax

master_pin : name ;

Example

master_pin : clk;

divided_by Simple Attribute

The divided_by attribute specifies the frequency division factor, which must be a power

of 2.

Syntax

divided_by : integer;

Example

generated_clock(genclk1) {

clock_pin : clk1;

master_pin : clk;

divided_by : 2;

invert : true;

}

This code fragment shows a clock pin (clk1) generated by dividing the original clock pin

(clk) frequency by 2 and then inverting the result.

multipled_by Simple Attribute

The multipled_by attribute specifies the frequency multiplication factor, which must be a

power of 2.

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Syntax

multipled_by : integer;

Example

generated_clock(genclk2) {

clock_pin : clk1;

master_pin : clk;

multiplied_by : 2;

duty_cycle : 50.0;

}

This code fragment shows a clock pin (clk1) generated by multiplying the original clock pin

(clk) frequency by 2, with a duty cycle of 50.

invert Simple Attribute

The invert attribute inverts the waveform generated by multiplication or division. Set this

attribute to true to invert the waveform. Set it to false if you do not want to invert the

waveform.

Syntax

invert : Boolean ;

Example

invert : true;

duty_cycle Simple Attribute

The duty_cycle attribute specifies the duty cycle, in percentage, if frequency

multiplication is used. This is a number between 0.0 and 100.0. The duty cycle is the high

pulse width.

Syntax

duty_cycle : float ;

Example

duty_cycle : 50.0;

edges Complex Attribute

The edges attribute specifies a list of three edges from the master clock that form the

edges of the generated clock. Use this option when simple division or multiplication is

insufficient to describe the generated clock waveform.

Syntax

edges (edge1,edge2,edge3);

Example

edges (1, 3, 5);

shifts Complex Attribute

The shifts attribute specifies the shifts (in time units) to be added to the edges specified

in the edge list to generate the clock. The number of shifts must equal the number of edges

(three). This shift modifies the ideal clock edges; it is not considered to be clock latency.

Syntax

shifts (shift1,shift2,shift3);

Example

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shifts (5.0, -5.0, 0.0);

Example 2-13 shows a generated clock description.

Example 2-13 Description of a Generated Clock

cell(acell) {

...

generated_clock(genclk1) {

clock_pin : clk1;

master_pin : clk;

divided_by : 2;

invert : true;

}

generated_clock(genclk2) {

clock_pin : clk1;

master_pin : clk;

multiplied_by : 2;

duty_cycle : 50.0;

}

generated_clock(genclk3) {

clock_pin : clk1;

master_pin : clk;

edges(1, 3, 5);

shifts(5.0, -5.0, 0.0);

}

....

pin(clk) {

direction : input;

clock : true;

capacitance : 0.1;

}

pin(clk1) {

direction : input;

clock : true;

capacitance : 0.1;

}

intrinsic_parasitic Group

The intrinsic_parasitic group specifies the state-dependent intrinsic capacitance

and intrinsic resistance of a cell.

Syntax

cell (namestring) {

intrinsic_parasitic (namestring) {

when : <boolean expression>;

intrinsic_resistance(<pg_pin_name>) {

related_output : <output_pin_name>;

value : < float>;

}

intrinsic_capacitance(<pg_pin_name>) {

value : <float>;

}

Simple Attribute

when

Groups

intrinsic_capacitance

intrinsic_resistance

total_capacitance

when Simple Attribute

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This attribute specifies the state-dependent condition that determines whether the intrinsic

parameters are accessed. An intrinsic_parasitic group without a when attribute is

defined as a default state. This state is associated with a non-state-dependent parasitic

model. If all the state conditions of a cell are specified, a default state is not required. If

some of the state conditions of a cell are missing, the default state will be assigned. If some

state conditions of a cell are missing and no default state is given, the value of

intrinsic_resistance defaults to +infinity and the value of

intrinsic_capacitance defaults to 0.

Syntax

when : <boolean expression>;

boolean expression

Specifies the state-dependent condition.

Example

when : "A B" ;

intrinsic_capacitance Group

Use this group to specify a cell’s intrinsic capacitance.

Syntax

cell (namestring) {

intrinsic_parasitic (namestring) {

intrinsic_capacitance (<pg_pin_name>) {

value : <float>;

}

The pg_pin_name specifies a power and ground pin where the capacitance is derived.

You can have more than one intrinsic_capacitance group. Groups can be placed in

any order within an intrinsic_parasitic group.

value Simple Attribute

Specifies the value of the intrinsic capacitance. If some of an intrinsic_capacitance

group is not defined, the value of the intrinsic capacitance defaults to 0.

Syntax

value : <float>;

Example

value : 5;

intrinsic_resistance Group

Use this group to specify a cell’s intrinsic resistance between a power and ground pin and

an output pin within the intrinsic_parasitic group in a cell.

Syntax

cell (namestring) {

intrinsic_parasitic (namestring) {

intrinsic_resistance (<pg_pin_name>) {

related_output : <output_pin_name>;

value : < float>;

}

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The pg_pin_name specifies a power or ground pin. The intrinsic_resistance

groups can be placed in any order within an intrinsic_parasitic group. If some of the

intrinsic_resistance group is not defined, the value of resistance defaults to +infinity.

The channel connection between the power and ground pin and the output pin is defined as

a closed channel if the resistance value is greater than 1 megohm. Otherwise, the channel

is opened. The intrinsic_resistance group is not required if the channel is closed.

Simple Attributes

related_output

value

related_output Simple Attribute

Use this attribute to specify the output pin.

Syntax

related_output : "output_pin_nameid ;

output_pin_name

The name of the output pin.

Example

related_outputs : "A B" ;

value Simple Attribute

Specifies the value of the intrinsic resistance. If some of an intrinsic_resistance

group is not defined, the value of the intrinsic resistance defaults to +infinity.

Syntax

value : <float>;

Example

value : 5;

total_capacitance Group

The total_capacitance group specifies the macro cell’s total capacitance on a power

or ground net within the intrinsic_parasitic group. The following applies to the

total_capacitance group:

● The total_capacitance group can be placed in any order if there is more

than one total_capacitance group within an intrinsic_parasitic

group.

● The total capacitance parasitics modeling in macros cells is not state dependent,

which means that there is no state condition specified in

intrinsic_parasitic.

Syntax

cell (cell_name) {

...

intrinsic_parasitic () {

total_capacitance (<pg_pin_name>) {

value : <float> ;

}

...

}

...

}

Example

cell (my_cell) {

...

intrinsic_parasitic () {

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total_capacitance (VDD) {

value : 0.2 ;

}

...

}

...

}

latch Group

A latch group is defined within a cell, model, or test_cell group to describe a level-

sensitive memory device. The syntax for defining a latch group within a cell group is

shown here. For information about test cells, see “test_cell Group ” .

library (namestring) {

cell (namestring) {

latch (variable1string, variable2string) {

... latch description ...

}

The variable1 value is the state of the noninverting output of the latch; the variable2

value is the state of the inverting output. The variable1 value is considered the 1-bit

storage of the latch. You can name variable1 and variable2 anything except a pin

name used in the cell being described. Both values are required, even if one of them is not

connected to a primary output pin.

Simple Attributes

clear : "Boolean expression" ;

clear_preset_var1 : L | H | N | T | X ;

clear_preset_var2 : L | H | N | T | X ;

data_in : "Boolean expression" ;

enable : "Boolean expression" ;

enable_also : "Boolean expression" ;

preset : "Boolean expression" ;

clear Simple Attribute

The clear attribute gives the active value for the clear input.

Syntax

clear : valueBoolean ;

Example

The following example defines a low-active clear signal.

clear : "CD’" ;

clear_preset_var1 and clear_preset_var2 Simple Attributes

The clear_preset_var1 and clear_preset_var2 attributes give the value that

variable1 and variable2 have when clear and preset are both active at the same

time.

Syntax

clear_preset_var1 : L | H | N | T | X ;

clear_preset_var2 : L | H | N | T | X ;

Table 2-9 shows the valid values for the clear_preset_var1 and clear_preset_var2

attributes.

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Table 2-9 Valid Values for the clear_preset_var1 and clear_preset_var2 Attributes

Variable values Equivalence

L 0

H 1

N No change1

T Toggle the current value from 1 to 0, 0 to 1, or X to X1

X Unknown1

1 Use these values to generate VHDL models.

See “Single-Stage Flip-Flop ” for more information about the clear_preset_var1 and

clear_preset_var2 attributes, including their function and values.

If you include both clear and preset, you must use either clear_preset_var1,

clear_preset_var2, or both. Conversely, if you include clear_preset_var1,

clear_preset_var2, or both, you must use both clear and preset.

Example

latch(IQ, IQN) {

clear : "S’" ;

preset : "R’" ;

clear_preset_var1 : L ;

clear_preset_var2 : L ;

}

data_in Simple Attribute

The data_in attribute gives the state of the data input, and the enable attribute gives the

state of the enable input. The data_in and enable attributes are optional, but if you use

one of them, you must also use the other.

Syntax

data_in : valueBoolean ;

value

State of data input.

Example

data_in : "D" ;

enable Simple Attribute

The enable attribute gives the state of the enable input, and data_in attribute gives the

state of the data input. The enable and data_in attributes are optional, but if you use

one of them, you must also use the other.

Syntax

enable : valueBoolean ;

value

State of enable input.

Example

enable : "G" ;

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enable_also Simple Attribute

The enable_also attribute gives the state of the enable input when you are describing

master and slave cells. The enable_also attribute is optional. If you use enable_also,

you must also use enable and data_in. attributes

Syntax

enable_also : "valueBoolean " ;

Value

State of enable input for master-slave cells.

Example

enable_also : "G" ;

preset Simple Attribute

The preset attribute gives the active value for the preset input.

Syntax

preset : "valueBoolean " ;

Example

The following example defines a low-active clear signal.

preset : "PD’" ;

Attribute Functions in a latch Group

The latch cell is activated whenever clear, preset, enable, or data_in changes.

Table 2-10 shows the functions of the attributes in the latch group.

Table 2-10 Function Table for a latch Group

enable clear preset variable1 variable2

active

inactive

data_in !data_in

-- active inactive

0 1

-- inactive

active 1 0

-- active active clear_preset_var1

clear_preset_var2

Example 2-14 shows a latch group for a D latch with active-high enable and negative

clear.

Example 2-14 D Latch With Active-High Enable and Negative Clear

latch(IQ, IQN) {

enable : "G" ;

data_in : "D" ;

clear : "CD’" ;

}

Example 2-15 shows a latch group for an SR latch. The enable and data_in attributes

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125

are not required for an SR latch.

Example 2-15 SR Latch

latch(IQ, IQN) {

clear : "S’" ;

preset : "R’" ;

clear_preset_var1 : L ;

clear_preset_var2 : L ;

}

latch_bank Group

A latch_bank group is defined within a cell, model, or test_cell group and in a

scaled_cell group at the library level to represent multibit latch registers. The syntax for

a cell is shown here. For information about test cells, see “test_cell Group ” .

The latch_bank group describes a cell that is a collection of parallel, single-bit sequential

parts. Each part shares control signals with the other parts and performs an identical

function.

An input pin that is described in a pin group, such as the clk input, is fanned out to each

latch in the bank. Each primary output must be described in a bus or bundle group, and

its function statement must include either variable1 or variable2.

The syntax of the latch_bank group is similar to that of the latch group (see “latch

Group ” ).

Syntax

library (namestring) {

cell (namestring) {

latch_bank(variable1string,variable2string,

bitsinteger){

... multibit latch register description ...

}

The bits value in the latch_bank definition is the number of bits in the multibit cell.

Simple Attributes

enable : "Boolean expression" ;

enable_also : "Boolean expression" ;

data_in : "Boolean expression" ;

clear : "Boolean expression" ;

preset : "Boolean expression" ;

clear_preset_var1 : L | H | N | T | X ;

clear_preset_var2 : L | H | N | T | X ;

Example 2-16 shows a latch_bank group for a multibit register containing four rising-

edge-triggered D latches.

Example 2-16 Multibit D Latch

cell (latch4) {

area: 16;

pin (G) { /* gate enable signal, active-high */

direction : input;

...

}

bundle (D) { /* data input with four member pins */

members(D1, D2, D3, D4);/*must be 1st bundle attribute*/

direction : input;

...

}

bundle (Q) {

members(Q1, Q2, Q3, Q4);

direction : output;

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function : "IQ" ;

...

}

bundle (QN) {

members (Q1N, Q2N, Q3N, Q4N);

direction : output;

function : "IQN";

...

}

latch_bank(IQ, IQN, 4) {

enable : "G" ;

data_in : "D" ;

}

...

}

clear Simple Attribute

The clear attribute gives the active value for the clear input.

Syntax

clear : "Boolean expression" ;

The following example defines a low-active clear signal.

clear : "CD’" ;

clear_preset_var1 and clear_preset_var2 Simple Attributes

The clear_preset_var1 and clear_preset_var2 attributes give the values that

variable1 and variable2 have when clear and preset are both active at the same

time.

Syntax

clear_preset_var1 : L | H | N | T | X ;

clear_preset_var2 : L | H | N | T | X ;

Example

See Table 2-9 for the valid values for the clear_preset_var1 and

clear_preset_var2 attributes.

See “Single-Stage Flip-Flop ” for more information about the clear_preset_var1 and

clear_preset_var2 attributes, including their function and values.

If you include both clear and preset, you must use either clear_preset_var1,

clear_preset_var2, or both. Conversely, if you include clear_preset_var1,

clear_preset_var2, or both, you must use both clear and preset.

latch_bank(IQ, IQN) {

clear : "S’" ;

preset : "R’" ;

clear_preset_var1 : L ;

clear_preset_var2 : L ;

}

data_in Simple Attribute

The data_in attribute gives the state of the data input, and the enable attribute gives the

state of the enable input. The enable and data_in attributes are optional, but if you use

one of them, you must also use the other.

Syntax

data_in : "Boolean expression" ;

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Boolean expression

State of data input.

Example

data_in : "D" ;

enable Simple Attribute

The enable attribute gives the state of the enable input, and the data_in attribute gives

the state of the data input. The enable and data_in attributes are optional, but if you use

one of them, you must include the other.

Syntax

enable : "Boolean expression" ;

Boolean expression

State of enable input.

Example

enable : "G" ;

preset Simple Attribute

The preset attribute gives the active value for the preset input.

Syntax

preset : "Boolean expression" ;

The following example defines a low-active clear signal.

preset : "PD’" ;

Attribute Functions in a latch_bank Group

The latch_bank cell is activated whenever the value of clear, preset, enable, or

data_in attribute changes.

Figure 2-2 and Example 2-17 show a multibit register containing four high-enable D latches

with the clear attribute.

Figure 2-2 Multibit Register With Latches

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Example 2-17 Multibit Register With Four D Latches

cell (DLT2) {

/* note: 0 hold time */

area : 1 ;

geometry_print : GP1 ;

pin (EN) {

direction : input ;

capacitance : 0 ;

min_pulse_width_low : 3 ;

min_pulse_width_high : 3 ;

}

bundle (D) {

members(DA, DB, DC, DD);

direction : input ;

capacitance : 0 ;

timing() {

related_pin : "EN" ;

timing_type : setup_falling ;

intrinsic_rise : 1.0 ;

intrinsic_fall : 1.0 ;

}

timing() {

related_pin : "EN" ;

timing_type : hold_falling ;

intrinsic_rise : 0.0 ;

intrinsic_fall : 0.0 ;

}

bundle (CLR) {

members(CLRA, CLRB, CLRC, CLRD);

direction : input ;

capacitance : 0 ;

timing() {

related_pin : "EN" ;

timing_type : recovery_falling ;

intrinsic_rise : 1.0 ;

intrinsic_fall : 0.0 ;

}

bundle (PRE) {

members(PREA, PREB, PREC, PRED);

direction : input ;

capacitance : 0 ;

timing() {

related_pin : "EN" ;

timing_type : recovery_falling ;

intrinsic_rise : 1.0 ;

intrinsic_fall : 0.0 ;

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}

latch_bank(IQ, IQN, 4) {

data_in : "D" ;

enable : "EN" ;

clear : "CLR’" ;

preset : "PRE’" ;

clear_preset_var1 : H ;

clear_preset_var2 : H ;

}

bundle (Q) {

members(QA, QB, QC, QD);

direction : output ;

function : "IQ" ;

timing() {

related_pin : "D" ;

intrinsic_rise : 2.0 ;

intrinsic_fall : 2.0 ;

}

timing() {

related_pin : "EN" ;

timing_type : rising_edge ;

intrinsic_rise : 2.0 ;

intrinsic_fall : 2.0 ;

}

timing() {

related_pin : "CLR" ;

timing_type : clear ;

timing_sense : positive_unate ;

intrinsic_fall : 1.0 ;

}

timing() {

related_pin : "PRE" ;

timing_type : preset ;

timing_sense : negative_unate ;

intrinsic_rise : 1.0 ;

}

bundle (QN) {

members(QNA, QNB, QNC, QND);

direction : output ;

function : "IQN" ;

timing() {

related_pin : "D" ;

intrinsic_rise : 2.0 ;

intrinsic_fall : 2.0 ;

}

timing() {

related_pin : "EN" ;

timing_type : rising_edge ;

intrinsic_rise : 2.0 ;

intrinsic_fall : 2.0 ;

}

timing() {

related_pin : "CLR" ;

timing_type : preset ;

timing_sense : negative_unate ;

intrinsic_rise : 1.0 ;

}

timing() {

related_pin : "PRE" ;

timing_type : clear ;

timing_sense : positive_unate ;

intrinsic_fall : 1.0 ;

}

} /* end of cell DLT2

leakage_current Group

A leakage_current group is defined within a cell group or a model group to specify

leakage current values that are dependent on the state of the cell.

Syntax

library (name) {

cell(<cell_name>) {

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...

leakage_current() {

when : <boolean expression>;

pg_current(<pg_pin_name>) {

value : <float>;

}

...

}

Simple Attribute

when

value

Group

pg_current

when Simple Attribute

This attribute specifies the state-dependent condition that determines whether the leakage

current is accessed.

A leakage_current group without a when attribute is defined as a default state. The

default state is associated with a leakage model that does not depend on the state

condition. If all state conditions of a cell are specified, a default state is not required. If

some state conditions of a cell are missing, the default state will be assigned. If no default

state is given, the leakage current defaults to 0.0.

Syntax

when : "Boolean expression" ;

Boolean expression

Specifies the state-dependent condition.

value Simple Attribute

When a cell has only a single power and ground pin, you can omit the pg_current group

and specify the leakage current value at this level. Otherwise, specify the value in the

pc_current group as shown below. Current conservation is applied for each

leakage_current group. The value attribute specifies the absolute value of leakage

current on a single power and ground pin.

Syntax

value : valuefloat ;

value

A floating-point number representing the leakage current.

pg_current Group

Use this group to specify a power or ground pin where leakage current is to be measured.

Syntax

cell(<cell_name>) { ... leakage_current

() { when : <boolean expression>; pg_current

(<pg_pin_name>) { value : <float>; }

pg_pin_name

Specifies the power or ground pin where the leakage current is to be

measured.

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Simple Attribute

value

Use this attribute in the pg_current group to specify the leakage current value when a

cell has multiple power and ground pins. The leakage current is measured toward a cell.

For power pins, the current is positive if it is dragged into a cell. For ground pins, the current

is negative, indicating that current flows out of a cell. If all power and ground pins are

specified within a leakage_current group, the sum of the leakage currents should be

zero.

Syntax

value : valuefloat ;

value

A floating-point number representing the leakage current.

gate_leakage Group

The gate_leakage group specifies the cell’s gate leakage current on input or inout pins

within the leakage_current group in a cell. The following applies to gate_leakage

groups:

● Groups can be placed in any order if there is more than one gate_leakage

group within a leakage_current group.The leakage current of a cell is

characterized with opened outputs, which means that modeling cell outputs do

not drive any other cells. Outputs are assumed to have zero static current during

the measurement.A missing gate_leakage group is allowed for certain pins.

Current conservation is applicable if it can be applied to higher error tolerance.

Syntax

gate_leakage (<an input pin name>)

Example

cell (my_cell) {

...

leakage_current {

...

}

...

gate_leakage (A) {

input_low_value : -0.5 ;

input_high_value : 0.6 ;

}

Simple Attributes

input_low_value

input_high_value

input_low_value Simple Attribute

The input_low_value attribute specifies gate leakage current on an input or inout pin

when the pin is in a low state condition. The following applies to the input_low_value

attribute:

● A negative floating-point number value is required.

● The gate leakage current flow is measured from the power pin of a cell to the

ground pin of its driver cell.

● The input pin is pulled up to low.

● The input_low_value attribute is not required for a gate_leakage group.

Syntax

input_low_value : <float> ;

Example

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}

...

gate_leakage (A) {

input_low_value : -0.5 ;

input_high_value : 0.6 ;

}

input_high_value Simple Attribute

The input_high_value attribute specifies gate leakage current on an input or inout pin

when the pin is in a high state condition.

● A positive floating-point number value is required.

● The gate leakage current flow is measured from the power pin of its driver cell to

the ground pin of the cell itself.

● The input pin is pulled up to high.

● The input_high_value attribute is not required for a gate_leakage group.

Syntax

input_high_value : <float> ;

Example

}

...

gate_leakage (A) {

input_low_value : -0.5 ;

input_high_value : 0.6 ;

}

leakage_power Group

A leakage_power group is defined within a cell group or a model group to specify

leakage power values that are dependent on the state of the cell.

Note:

Cells with state-dependent leakage power also need the cell_leakage_power simple

attribute.

Syntax

library (name) {

cell (name) {

leakage_power () {

...

}

Simple Attributes

power_level

related_pg_pin

when

value

power_level Simple Attribute

Use this attribute to specify the power consumed by the cell.

Syntax

power_level : "name" ;

name

Name of the power rail defined in the power supply group.

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Example

power_level : "VDD1" ;

related_pg_pin Simple Attribute

Use this optional attribute to associate a power and ground pin with leakage power and

internal power tables. The leakage power and internal energy tables can be omitted when

the voltage of a primary_power or backup_ground pg_pin is at reference voltage

zero, since the value of the corresponding leakage power and internal energy tables will

always be zero.

In the absence of a related_pg_pin attribute, the internal_power/leakage_power

specifications apply to the whole cell (cell-specific power specification).Cell-specific and

pg_pin-specific power specifications cannot be mixed; that is, when one leakage_power

(internal_power) group has the related_pg_pin attribute, all the leakage_power

(internal_power) groups must have the related_pg_pin attribute.

Syntax

related_pg_pin : pg_pinid;

pg_pin

The related power and ground pin name.

Example

related_pg_pin : G2 ;

when Simple Attribute

This attribute specifies the state-dependent condition that determines whether the leakage

power is accessed.

Syntax

when : "Boolean expression" ;

Boolean expression

Name of pin or pins in a cell for which leakage_power is different.

Table 2-11 lists the Boolean operators valid in a when statement.

Table 2-11 Valid Boolean Operators

Operator Description

' invert previous expression

! invert following expression

^ logical XOR

* logical AND

& logical AND

space logical AND

+ logical OR

| logical OR

1 signal tied to logic 1

0 signal tied to logic 0

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value Simple Attribute

Use this attribute to specify the leakage power for a given state of a cell.

Syntax

value : valuefloat ;

value

A floating-point number representing the leakage power value.

The following example defines the leakage_power group and the

cell_leakage_power simple attribute in a cell:

Example

cell () {

...

leakage_power () {

when : "A" ;

value : 2.0 ;

}

cell_leakage_power : 3.0 ;

}

lut Group

A lut group defines a single variable that is then used to represent the lookup table value

in the function attribute of a pin group. The lut group applies only to FPGA libraries.

Syntax

library (namestring) {

cell (namestring) {

lut (name) {

... ;

}

Example

cell () {

...

lut(L) {

input_pins : "A B C D" ;

}

pin (Z){

...

function: "L" ;

}

input_pins Simple Attribute

input_pins : "name1 [name2 name3 ...]" ;

mode_definition Group

A mode_definition group declares a mode group that contains several timing mode

values. Each timing arc can be enabled based on the current mode of the design, which

results in different timing for different modes. You can optionally put a condition on a mode

value. When the condition is true, the mode group takes that value.

Syntax

cell (namestring) {

mode_definition (namestring) (

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...

}

Group Statement

mode_value (namestring) { }

mode_value Group

Use this group to specify a timing mode.

Simple Attributes

when

sdf_cond

when Simple Attribute

The when attribute specifies the condition that a timing arc depends on to activate a path.

The valid value is a Boolean expression.

Syntax

when : Boolean expression ;

Example

when: !R;

sdf_cond Simple Attribute

The sdf_cond attribute supports Standard Delay Format (SDF) file generation and

condition matching during back-annotation.

Syntax

sdf_cond : sdf_expressionstring ;

Example

sdf_cond: "R == 0";

Example 2-18 shows a mode_definition description.

Example 2-18 mode_definition Description

cell(sample_cell) {

...

mode_definition(rw) {

mode_value(read) {

when : "R";

sdf_cond : "R == 1";

}

mode_value(write) {

when : "!R";

sdf_cond : "R == 0";

}

pg_pin Group

Use the pg_pin group to specify power and ground pins. The library cells can have

multiple pg_pin groups. A pg_pin group is mandatory for each cell. A cell must have at

least one primary_power pin specified in the pg_type attribute and at least one

primary_ground pin specified in the pg_type attribute.

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Syntax

cell (namestring){

pg_pin (pg_pin_namestring){

voltage_name : valueid ;

pg_type : valueenum ; } /* end pg_pin

*/ ... }/* end cell */

Simple Attributes

voltage_name

pg_type

voltage_name Simple Attribute

Use the voltage_name attribute to specify an associated voltage.

Syntax

voltage_name : valueid ;

value

A voltage defined in a library-level voltage_map attribute.

Example

voltage_name : VDD1 ;

pg_type Simple Attribute

Use the optional pg_type attribute to specify the type of power and ground pin.

Syntax

pg_type : valueenum ;

value

The valid values are primary_power, primary_ground,

backup_power, backup_ground, internal_power, and

internal_ground.

Example

pg_type : primary_power ;

routing_track Group

A routing_track group is defined at the cell group or model group level:

Syntax

library (namestring){

cell (namestring){

routing_track (routing_layer_namestring){

... routing track description ...

}

Simple Attributes

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tracks : integer ;

total_track_area : float ;

Complex Attribute

short /* for model group only */

tracks Simple Attribute

The tracks attribute indicates the number of tracks available for routing on any particular

layer.

Syntax

tracks : valueint ;

value

A number larger than or equal to 0.

Example

tracks : 2 ;

total_track_area Simple Attribute

The total_track_area attribute specifies the total routing area of the routing tracks.

Syntax

total_track_area : valuefloat ;

value

A floating-point number larger than or equal to 0.0 and less than or equal to

the area on the cell.

Example

total_track_area : 0.2 ;

statetable Group

The statetable group captures the function of more-complex sequential cells. It is

defined in a cell group, model group, scaled_cell group, or test_cell group.

The purpose of this group is to define a state table. A state table is a sequential lookup

table. It takes an arbitrary number of inputs and their delayed values and an arbitrary

number of internal nodes and their delayed values to form an index to new internal node

values.

Note:

In the statetable group, table is a keyword.

Syntax

statetable( "input node names", "internal node names" ) {

table : " input node values : current internal values :\

next internal values,

\ input node values : current internal values : \

next internal values";

}

The following example shows a state table for a JK flip-flop with an active-low, direct-clear,

and negative-edge clock:

Example

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statetable ("J K CN CD", "IQ" ) {

table: "- - - L : - : L,\

- - ~F H : - : N,\

L L F H :L/H: L/H,\

H L F H : - : H,\

L H F H : - : L,\

H H F H :L/H: H/L" ;

}

test_cell Group

The test_cell group is in a cell group or model group. It models only the nontest

behavior of a scan cell, which is described by an ff, ff_bank, latch, latch_bank or

statetable statement and pin function attributes.

Syntax

library (namestring) {

cell (namestring) {

test_cell () {

... test cell description ...

}

You do not need to give the test cell a name, because the test cell takes the name of the

cell being defined.

Groups

ff (variable1id, variable2id) { }

ff_bank (variable1id, variable2string, bitsint) { }

latch (variable1id, variable2id) { }

latch_bank (variable1id, variable2id, bitsint){}

pin (nameid) { }

statetable ("input node names", "internal node names") { }

ff Group

For a discussion of the ff group syntax, see “ff Group ” .

ff_bank Group

For a discussion of the ff_bank group syntax, see “ff_bank Group ” .

latch Group

For a discussion of the latch group syntax, see “latch Group ” .

latch_bank Group

For a discussion of the latch_bank group syntax, see “latch_bank Group ” .

pin Group in a test_cell Group

Both test pin and nontest pin groups appear in pin groups within a test_cell group:

library (namestring) {

cell (namestring) {

test_cell (namestring) {

pin (namestring | name_liststring) {

... pin description ...

}

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These groups are similar to pin groups in a cell group or model group but can contain

only direction, function, signal_type, and test_output_only attributes. They

cannot contain timing, capacitance, fanout, or load information.

Simple Attributes

direction : input | output | inout ;

function : Boolean expression ;

signal_type: test_scan_in | test_scan_in_inverted |

test_scan_out |test_scan_out_inverted |

test_scan_enable| test_scan_enable_inverted |

test_scan_clock | test_scan_clock_a |

test_scan_clock_b | test_clock ;

test_output_only : true | false ;

Group

statetable() { }

direction Attribute

The direction attribute states whether the pin being described is an input, output, or

inout (bidirectional) pin. The default is input.

Syntax

direction : input | output | inout ;

Example

direction : input ;

function Attribute

The function attribute reflects only the nontest behavior of a cell.

An output pin must have either a function attribute or a signal_type attribute.

The function attribute in a pin group defines the value of an output pin or inout pin in

terms of the input pins or inout pins in the cell group or model group. For more details

about function, see the “function Simple Attribute ” .

Syntax

function : "Boolean expression" ;

Boolean expression

Identifies the replaced cell.

Example

function : "IQ" ;

signal_type Attribute

In a test_cell group, signal_type identifies the type of test pin.

Syntax

signal_type : "value";

Descriptions of the possible values for the signal_type attribute follow:

test_scan_in

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Identifies the scan-in pin of a scan cell. The scanned value is the same as

the value present on the scan-in pin. All scan cells must have a pin with

either the test_scan_in or the test_scan_in_inverted attribute.

test_scan_in_inverted

Identifies the scan-in pin of a scan cell as being of inverted polarity. The

scanned value is the inverse of the value present on the scan-in pin.

For multiplexed flip-flop scan cells, the polarity of the scan-in pin is inferred

from the latch or ff declaration of the cell itself. For other types of scan

cells, clocked-scan, level-sensitive scan design (LSSD), and multiplexed

flip-flop latches, it is not possible to give the ff or latch declaration of the

entire scan cell. For these cases, you can use the

test_scan_in_inverted attribute in the cell where the scan-in pin

appears in the latch or ff declarations for the entire cell.

test_scan_out

Identifies the scan-out pin of a scan cell. The value present on the scan-out

pin is the same as the scanned value. All scan cells must have a pin with

either a test_scan_out or a test_scan_out_inverted attribute.

The scan-out pin corresponds to the output of the slave latch in the LSSD

methodologies.

test_scan_out_inverted

Identifies the scan-out of a test cell as having inverted polarity. The value

on this pin is the inverse of the scanned value.

test_scan_enable

Identifies the pin of a scan cell that, when high, indicates that the cell is

configured in scan-shift mode. In this mode, the clock transfers data from

the scan-in input to the scan-out input.

test_scan_enable_inverted

Identifies the pin of a scan cell that, when low, indicates that the cell is

configured in scan-shift mode. In this mode, the clock transfers data from

the scan-in input to the scan-out input.

test_scan_clock

Identifies the test scan clock for the clocked-scan methodology. The signal

is assumed to be edge-sensitive. The active edge transfers data from the

scan-in pin to the scan-out pin of a cell. The sense of this clock is

determined by the sense of the associated timing arcs.

test_scan_clock_a

Identifies the a clock pin in a cell that supports the single-latch LSSD,

double-latch LSSD, clocked LSSD, or auxiliary clock LSSD methodologies.

When the a clock is at the active level, the master latch of the scan cell can

accept scan-in data. The sense of this clock is determined by the sense of

the associated timing arcs.

test_scan_clock_b

Identifies the b clock pin in a cell that supports the single-latch LSSD,

clocked LSSD, or auxiliary clock LSSD methodologies. When the b clock is

at the active level, the slave latch of the scan-cell can accept the value of

the master latch. The sense of this clock is determined by the sense of the

associated timing arcs.

test_clock

Identifies an edge-sensitive clock pin that controls the capturing of data to

fill scan-in test mode in the auxiliary clock LSSD methodology.

If an input pin is used in both test and nontest modes (such as the clock input in the

multiplexed flip-flop methodology), do not include a signal_type statement for that pin itn

the test_cell pin definition.

If an input pin is used only in nontest mode and does not exist on the cell that it will scan

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141

and replace, you must include a signal_type statement for that pin in the test_cell

pin definition.

If an output pin is used in nontest mode, it needs a function statement. The

signal_type statement is used to identify an output pin as a scan-out pin. In a

test_cell group, the pin group for an output pin can contain a function statement, a

signal_type attribute, or both.

You do not have to define a function or signal_type attribute in the pin group if the

pin is defined in a previous test_cell group for the same cell.

Example

signal_type : "test_scan_in" ;

test_output_only Attribute

This attribute is an optional Boolean attribute that you can set for any output port described

in statetable format.

In ff/latch format, if a port is to be be used for both function and test, you provide the

functional description using the function attribute. If a port is to be used for test only, you

omit the function attribute.

In statetable format, however, a port always has a functional description. Therefore, if you

want to specify that a port is for test only, you set the test_output_only attribute to true.

Syntax

test_output_only : true | false ;

Example

test_output_only : true ;

statetable Group

For a discussion of the statetable group syntax, see “statetable Group ” .

type Group

The type group, when defined within a cell, is a type definition local to the cell. It cannot be

used outside of the cell.

Syntax

cell (namestring) {

type (namestring) {

... type description ...

}

Simple Attributes

base_type : array ;

bit_from : integer ;

bit_to : integer ;

bit_width : integer ;

data_type : bit ;

downto : Boolean ;

base_type Simple Attribute

The only valid base type value is array .

Example

base_type : array ;

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bit_from Simple Attribute

The bit_from attribute specifies the member number assigned to the most significant bit

(MSB) of successive array members.

Syntax

bit_from : valueint ;

value

Indicates the member number assigned to the MSB of successive array

members. The default is 0.

Example

bit_from : 0 ;

bit_to Simple Attribute

The bit_to attribute specifies the member number assigned to the least significant bit

(LSB) of successive array members.

Syntax

bit_to : valueint ;

value

Indicates the member number assigned to the LSB of successive array

members. The default is 0.

Example

bit_to : 3 ;

bit_width Simple Attribute

The bit_width attribute specifies the integer that designates the number of bus

members.

Syntax

bit_width : valueint ;

value

Designates the number of bus members. The default is 1.

Example

bit_width : 4 ;

data_type Simple Attribute

Only the bit data type is supported.

Example

data_type : bit ;

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downto Simple Attribute

The downto attribute specifies a Boolean expression that indicates whether the MSB is

high or low.

Syntax

downto : true | false ;

true

Indicates that member number assignment is from high to low. The default

is false (low to high).

Example 2-19 illustrates a type group statement in a cell.

Example 2-19 type Group Within a Cell

cell (buscell4) {

type (BUS4) {

base_type : array ;

data_type : bit ;

bit_width : 4 ;

bit_from : 0 ;

bit_to : 3 ;

downto : true ;

}

2.2 model Group

A model group is defined within a library group, as shown here:

Syntax

library (namestring) {

model (namestring) {

... model description ...

}

2.2.1 Attributes and Values

A model group can include all the attributes that are valid in a cell group, as well as the

two additional attributes described in this section. For information about the cell group

attributes, see “Attributes and Values” .

Simple Attribute

cell_name

Complex Attribute

short

cell_name Simple Attribute

The cell_name attribute specifies the name of the cell within a model group.

Syntax

cell_name : "namestring" ;

Example

model(modelA) {

cell_name : "cellA";

...

}

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short Complex Attribute

The short attribute lists the shorted ports that are connected together by a metal or poly

trace. These ports are modeled within a model group.

The most common example of shorted port is a feedthrough, where an input port is directly

connected to an output port. Another example is two output ports that fan out from the

same gate.

Syntax

short ("name_liststring") ;

Example

short(b, y);

Example 2-20 shows how to use a short attribute in a model group.

Example 2-20 Using the short Attribute in a model Group

model(cellA) {

area : 0.4;

...

short(b, y);

short(c, y);

short(b, c);

...

pin(y) {

direction : output;

timing() {

related_pin : a;

...

}

pin(a) {

direction : input;

capacitance : 0.1;

}

pin(b) {

direction : input;

capacitance : 0.1;

}

pin(c) {

direction : input;

capacitance : 0.1;

clock : true;

}

3. pin Group Description and Syntax

You can define a pin group within a cell, test_cell, scaled_cell, model, or bus

group.

This chapter contains

● An example of the pin group syntax showing the attribute and group statements

that you can use within the pin group

● Descriptions of the attributes and groups you can use in a pin group

3.1 Syntax of a pin Group in a cell or bus Group

A pin group can include simple and complex attributes and group statements. In a cell or

bus group, the syntax of a pin group is as follows:

library (name) {

cell (name) {

pin (name | name_list) {

... pin description ...

}

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}

cell (name) {

bus (name) {

pin (name | name_list) {

... pin description ...

}

3.1.1 pin Group Example

Example 3-1 shows pin groups with CMOS library attributes and a timing group.

Example 3-1 CMOS pin Group Example

library(example){

date : "November 12, 2002" ;

revision : 2.3 ;

...

cell(AN2) {

area : 2 ;

pin(A) {

direction : input ;

dont_fault : true ;

capacitance : 1.3 ;

fanout_load : 2 ; /* internal fanout load */

max_transition : 4.2 ;/* design-rule constraint */

}

pin(B) {

direction : input ;

capacitance : 1.3 ;

}

pin(Z) {

direction : output ;

function : "A * B" ;

max_transition : 5.0 ;

timing() {

intrinsic_rise : 0.58 ;

intrinsic_fall : 0.69 ;

rise_resistance : 0.1378 ;

fall_resistance : 0.0465 ;

related_pin : "A B" ;

}

3.1.2 Simple Attributes

Example 3-2 lists alphabetically a sampling of the attributes and groups that you can define

within a pin group.

Example 3-2 Attributes and Values in a pin Group

/* Simple Attributes in a pin Group */

bit_width : integer ; /* bus cells */

capacitance : float ;

clock : true | false ;

clock_gate_clock_pin : true | false ;

clock_gate_enable_pin : true | false ;

clock_gate_test_pin : true | false ;

clock_gate_obs_pin : true | false ;

clock_gate_out_pin : true | false ;

complementary_pin : "string" ;

connection_class : "name1 [name2 name3 ... ]" ;

direction : input | output | inout | internal ;

dont_fault : sa0 | sa1 | sao1 ;

drive_current : float ;

| resistive_0 | resistive_1 ;

fall_capacitance : float ;

fall_current_slope_after_threshold : float ;

fall_current_slope_before_threshold : float ;

fall_time_after_threshold : float ;

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fall_time_before_threshold : float ;

fanout_load : float ;

fault_model : "two-value string" ;

function : "Boolean expression" ;

has_builtin_pad : Boolean expression ;

hysteresis : true | false ;

input_map : "namestring | name_list" ;

input_signal_level : string ;

input_voltage : string ;

internal_node : namestring ; /* Required in statetable cells */

inverted_output : true | false ;/* Required in statetable cells */

is_pad : true | false ;

max_capacitance : float ;

max_fanout : float ;

max_input_noise_width : float ;

max_transition : float ;

min_capacitance : float ;

min_fanout : float ;

min_input_noise_width : float ;

min_period : float ;

min_pulse_width_high : float ;

min_pulse_width_low : float ;

min_transition : float ;

multicell_pad_pin : true | false ;

output_signal_level : string ;

output_voltage : string ;

pin_func_type : clock_enable| active_high | active_low |

active_rising | active_falling ;

prefer_tied : "0" | "1" ;

primary_output : true | false ;

pulling_current : current value ;

pulling_resistance : resistance value;

rise_capacitance : float ;

rise_current_slope_after_threshold : float ;

rise_current_slope_before_threshold : float ;

rise_time_after_threshold : float ;

rise_time_before_threshold : float ;

signal_type : test_scan_in | test_scan_in_inverted | test_scan_out |

test_scan_out_inverted | test_scan_enable |

test_scan_enable_inverted |test_scan_clock |

test_scan_clock_a | test_scan_clock_b | test_clock ;

slew_control : low | medium | high | none ;

state_function : "Boolean expression" ;

test_output_only : true | false ;

three_state : "Boolean expression" ;

vhdl_name : "string" ;

x_function : "Boolean expression" ;

/* Complex Attributes in a pin Group */

fall_capacitance_range ( float, float) ;

rise_capacitance_range ( float, float) ;

/* Group Statements in a pin Group */

electromigration () { }

hyperbolic_noise_above_high () { }

hyperbolic_noise_below_low () { }

hyperbolic_noise_high () { }

hyperbolic_noise_low () { }

internal_power () { }

max_trans () { }

min_pulse_width () { }

minimum_period () { }

timing () { }

tlatch () {}

bit_width Simple Attribute

An integer that designates the number of bus members. The default is 1.

Syntax

bit_width : integer ;

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Example

bit_width : 4 ;

capacitance Simple Attribute

The capacitance attribute defines the load of an input, output, inout, or internal pin.

Syntax

capacitance : valuefloat ;

value

A floating-point number in units consistent with other capacitance

specifications throughout the library. Typical units of measure for

capacitance include picofarads and standardized loads.

Example

The following example defines the A and B pins in an AND cell, each with a capacitance of

one unit.

cell (AND) {

area : 3 ;

vhdl_name : "AND2" ;

pin (A,B) {

direction : input ;

capacitance : 1 ;

}

clock Simple Attribute

The clock attribute indicates whether an input pin is a clock pin.

Syntax

clock : true | false ;

A true value labels a pin as a clock pin. A false value labels a pin as not a clock pin, even

though it may otherwise have such characteristics.

Example

The following example defines pin CLK2 as a clock pin.

pin(CLK2) {

direction : input ;

capacitance : 1.0 ;

clock : true ;

}

clock_gate_clock_pin Simple Attribute

The clock_gate_clock_pin attribute identifies an input pin connected to a clock signal.

Syntax

clock_gate_clock_pin : true | false ;

A true value labels the pin as a clock pin. A false value labels the pin as not a clock pin.

Example

clock_gate_clock_pin : true ;

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clock_gate_enable_pin Simple Attribute

The clock_gate_enable_pin attribute identifies an input port connected to an enable

signal for nonintegrated clock-gating cells and integrated clock-gating cells.

Syntax

clock_gate_enable_pin : true | false ;

A true value labels the input port pin connected to an enable signal for nonintegrated and

integrated clock-gating cells. A false value labels the input port pin connected to an enable

signal as not for nonintegrated and integrated clock-gating cells.

Example

clock_gate_enable_pin : true ;

For nonintegrated clock-gating cells, you can set the clock_gate_enable_pin attribute

to true on only one input port of a 2-input AND, NAND, OR, or NOR gate. If you do so, the

other input port is the clock.

clock_gate_test_pin Simple Attribute

The clock_gate_test_pin attribute identifies an input pin connected to a test_mode or

scan_enable signal.

Syntax

clock_gate_test_pin : true | false ;

A true value labels the pin as a test (test_mode or scan_enable) pin. A false value labels

the pin as not a test pin.

Example

clock_gate_test_pin : true ;

clock_gate_obs_pin Simple Attribute

The clock_gate_obs_pin attribute identifies an output pin connected to an observability

signal.

Syntax

clock_gate_obs_pin : true | false ;

A true value labels the pin as an observability pin. A false value labels the pin as not an

observability pin.

Example

clock_gate_obs_pin : true ;

clock_gate_out_pin Simple Attribute

The clock_gate_out_pin attribute identifies an output port connected to an

enable_clock signal.

Syntax

clock_gate_out_pin : true | false ;

A true value labels the pin as an out (enable_clock) pin. A false value labels the pin as not

an out pin.

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Example

clock_gate_out_pin : true ;

complementary_pin Simple Attribute

The complementary_pin attribute supports differential I/O. Differential I/O assumes the

following:

● When the noninverting pin equals 1 and the inverting pin equals 0, the signal

gets logic 1.

● When the noninverting pin equals 0 and the inverting pin equals 1, the signal

gets logic 0.

Use the complementary_pin attribute to identify the differential input inverting pin with

which the noninverting pin is associated and from which it inherits timing information and

associated attributes.

For information on the connection_class attribute, see “connection_class Simple

Attribute ” .

Syntax

complementary_pin : "valuestring" ;

value

Identifies the differential input data inverting pin whose timing information

and associated attributes the noninverting pin inherits. Only one input pin is

modeled at the cell level. The associated differential inverting pin is defined

in the same pin group as the noninverting pin.

For details on the fault_model attribute that you use to define the value

when both the complementary pins are driven to the same value, see

“fault_model Simple Attribute” .

Example

cell (diff_buffer) {

...

pin (A) { /* noninverting pin /

direction : input ;

complementary_pin : ("DiffA") /* inverting pin /

}

connection_class Simple Attribute

The connection_class attribute defines design rules for connections between cells.

Only pins with the same connection class can be legally connected.

Syntax

connection_class : "name1 [name2 name3 ... ]" ;

name

A name or names of your choice for the connection class. You can assign

multiple connection classes to a pin by separating the connection class

names with spaces.

Example

connection_class : "internal" ;

direction Simple Attribute

The direction attribute declares a pin as being an input, output, inout (bidirectional), or

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internal pin. The default is input.

Syntax

direction : input | output | inout | internal ;

Example

In the following example, both A and B in the AND cell are input pins; Y is an output pin.

cell (AND) {

area : 3 ;

vhdl_name : "AND2" ;

pin (A,B) {

direction : input ;

}

pin (Y) {

direction : output ;

}

dont_fault Simple Attribute

The dont_fault attribute is a string (“stuck at”) that you can set on a library cell or pin.

Syntax

dont_fault : sa0 | sa1 | sa01 ;

Example

dont_fault : sa0;

The dont_fault attribute can also be defined in the cell group.

drive_current Simple Attribute

The drive_current attribute defines the drive current strength for the pad pin.

Syntax

drive_current : valuefloat ;

value

A floating-point number that represents the drive current the pad supplies

in the units defined with the current_unit library-level attribute.

Example

drive_current : 5.0 ;

driver_type Simple Attribute

The driver_type attribute tells the VHDL library generator to use a special pin-driving

configuration for the pin during simulation.

Syntax

driver_type : pull_up | pull_down | open_drain

pull_up

The pin is connected to power through a resistor. If it is a three-state output

pin, it is in the Z state and its function is evaluated as a resistive 1 (H). If it

is an input or inout pin and the node to which it is connected is in the Z

state, it is considered an input pin at logic 1 (H). For a pull-up cell, the pin

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constantly stays at logic 1 (H).

pull_down

The pin is connected to ground through a resistor. If it is a three-state

output pin, it is in the Z state and its function is evaluated as a resistive 0

(L). If it is an input or inout pin and the node to which it is connected is in

the Z state, it is considered an input pin at logic 0 (L). For a pull-down cell,

the pin constantly stays at logic 0 (L).

open_drain

The pin is an output pin without a pull-up transistor. Use this driver type

only for off-chip output or inout pins representing pads. The pin goes to

high impedance (Z) when its function is evaluated as logic 1.

open_source

The pin is an output pin without a pull-down transistor. Use this driver type

only for off-chip output or inout pins representing pads. The pin goes to

high impedance (Z) when its function is evaluated as logic 0.

bus_hold

The pin is a bidirectional pin on a bus holder cell. The pin holds the last

logic value present at that pin when no other active drivers are on the

associated net. Pins with this driver type cannot have function or

three_state statements.

resistive

The pin is an output pin connected to a controlled pull-up or pull-down

transistor with a control port EN. When EN is disabled, the pull-up or pull-

down transistor is turned off and has no effect on the pin. When EN is

enabled, a functional value of 0 evaluated at the pin is turned into a weak

0, and a functional value of 1 is turned into a weak 1, but a functional value

of Z is not affected.

resistive_0

The pin is an output pin connected topower through a pull-up transistor that

has a control port EN. When EN is disabled, the pull-up transistor is turned

off and has no effect on the pin. When EN is enabled, a functional value of

1 evaluated at the pin turns into a weak 1, but a functional value of 0 or Z is

not affected.

resistive_1

The pin is an output pin connected toground through a pull-down transistor

that has a control port EN. When EN is disabled, the pull-down transistor is

turned off and has no effect on the pin. When EN is enabled, a functional

value of 0 evaluated at the pin turns into a weak 0, but a functional value of

1 or Z is not affected.

Table 3-1 lists the driver types, their signal mappings, and the applicable pin types.

Table 3-1 Pin Driver Types

Driver type Signal mapping Pin

pull_up 01Z->01H in, out

pull_down 01Z->01L in, out

open_drain 01Z->0ZZ out

open_source

01Z->0Z1Z out

bus_hold 01Z->01S inout

resistive 01Z->LHZ out

resistive_0 01Z->0HZ out

resistive_1 01Z->L1Z out

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Following are important concepts to keep in mind when interpreting Table 3-1.

● The signal modifications a driver_type attribute defines divide into two

categories, transformation and resolution.

❍ Transformation specifies an actual signal transition from 0/1 to L/H/Z. This signal

transition performs a function on an input signal and requires only a

straightforward mapping.

❍ Resolution resolves the value Z on an existing circuit node without actually

performing a function and implies a constant (0/1) signal source as part of the

resolution.

In Table 3-1, the pull_up, pull_down, and bus_hold driver types define a

resolution scheme. The remaining driver types define transformations.

Example 3-3 describes an output pin with a pull-up resistor and the bidirectional pin on a

bus_hold cell.

Example 3-3 Pin Driver Type Specifications

cell (bus) {

pin(Y) {

direction : output ;

driver_type : pull_up ;

pulling_resistance : 10000 ;

function : "IO" ;

three_state : "OE" ;

}

cell (bus_hold) {

pin(Y) {

direction : inout ;

driver_type : bus_hold ;

}

Bidirectional pads often require one driver type for the output behavior and another driver

type associated with the input behavior. In such a case, define multiple driver types in one

driver_type attribute, as shown here:

driver_type : open_drain pull_up ;

Note:

An n-channel open-drain pad is flagged with open_drain, and a p-channel open-drain pad

is flagged with open_source.

driver_waveform Simple Attribute

The driver_waveform attribute specified at the pin level is the same as the

driver_waveform attribute specified at the cell level. For more information, see

“driver_waveform Simple Attribute” .

driver_waveform_rise and driver_waveform_fall Simple Attributes

The driver_waveform_rise and driver_waveform_fall attributes specified at the

pin level are the same as the driver_waveform_rise and driver_waveform_fall

attributes specified at the cell level. For more information, see “driver_waveform_rise and

driver_waveform_fall Simple Attributes” .

fall_capacitance Simple Attribute

Defines the load for an input and inout pin when its signal is falling.

Setting a value for the fall_capacitance attribute requires that a value for

rise_capacitance also be set, and setting a value for rise_capacitance attribute

requires that a value for the fall_capacitance also be set.

Syntax

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fall_capacitance : float ;

float

A floating-point number that represents the internal fanout of the input pin.

Typical units of measure for fall_capacitance include picofarads and

standardized loads.

Example

The following example defines the A and B pins in an AND cell, each with a

fall_capacitance of one unit, a rise_capacitance of two units, and a

capacitance of two units.

cell (AND) {

area : 3 ;

vhdl_name : "AND2" ;

pin (A,B) {

direction : input ;

fall_capacitance : 1 ;

rise_capacitance : 2 ;

capacitance : 2 ;

}

fall_current_slope_after_threshold Simple Attribute

The fall_current_slope_after_threshold attribute represents a linear

approximation of the change in current with respect to time, from the point at which the

rising transition reaches the threshold to the end of the transition.

Syntax

fall_current_slope_after_threshold : valuefloat ;

value

A floating-point number that represents the change in current.

Example

fall_current_slope_after_threshold : 0.07 ;

fall_current_slope_before_threshold Simple Attribute

The fall_current_slope_before_threshold attribute represents a linear

approximation of the change in current with respect to time from the beginning of the falling

transition to the threshold point.

Syntax

fall_current_slope_before_threshold : valuefloat ;

value

A floating-point number that represents the change in current.

Example

fall_current_slope_before_threshold : -0.14 ;

fall_time_after_threshold Simple Attribute

The fall_time_after_threshold attribute gives the time interval from the threshold

point of the falling transition to the end of the transition.

Syntax

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fall_time_after_threshold : valuefloat ;

value

A floating-point number that represents the time interval.

Example

fall_time_after_threshold : 1.8 ;

fall_time_before_threshold Simple Attribute

The fall_time_before_threshold attribute gives the time interval from the beginning

of the falling transition to the point at which the threshold is reached.

Syntax

fall_time_before_threshold : valuefloat ;

value

A floating-point number that represents the time interval.

Example

fall_time_before_threshold : 0.55 ;

fanout_load Simple Attribute

The fanout_load attribute gives the internal fanout load for an input pin.

Syntax

fanout_load : valuefloat ;

value

A floating-point number that represents the internal fanout of the input pin.

There are no fixed units for fanout_load. Typical units are standard

loads or pin count.

Example

pin (B) {

direction : input ;

fanout_load : 2.0 ;

}

fault_model Simple Attribute

The differential I/O feature enables an input noninverting pin to inherit the timing information

and all associated attributes of an input inverting pin in the same pin group designated

with the complementary_pin attribute.

The fault_model attribute defines a two-value string when both differential inputs are

driven to the same value. The first value represents the value when both input pins are at

logic 0, and the second value represents the value when both input pins are at logic 1.

For details on the complementary_pin attribute, see “complementary_pin Simple

Attribute ” .

Syntax

fault_model : "two-value string" ;

two-value string

Two values that define the value of the differential signals when both inputs

are driven to the same value. The first value represents the value when

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both input pins are at logic 0; the second value represents the value when

both input pins are at logic 1. Valid values for the two-value string are any

two-value combinations made up of 0, 1, and x.

If you do not enter a fault_model attribute value, the signal pin value

goes to x when both input pins are 0 or 1.

Example

cell (diff_buffer) {

...

pin (A) { /* noninverting pin /

direction : input ;

complementary_pin : ("DiffA")

fault_model : "1x" ;

}

function Simple Attribute

The function attribute describes the value of a pin or bus.

Pin Names as function Statement Arguments

The function attribute in a pin group defines the value of an output pin or inout pin in

terms of the input pins or inout pins in the cell group.

Syntax

function : "Boolean expression" ;

Table 3-2 lists the valid Boolean operators in a function statement. The precedence of the

operators is left to right, with inversion performed first, then XOR, then AND, then OR

Table 3-2 Valid Boolean Operators

Operator Description

' invert previous expression

! invert following expression

^ logical XOR

* logical AND

& logical AND

space logical AND

+ logical OR

| logical OR

1 signal tied to logic 1

0 signal tied to logic 0

The following example describes pin Q with the function A OR B.

Example

pin(Q) {

direction : output ;

function : "A + B" ;

}

Note:

Pin names beginning with a number, and pin names containing special characters, must be

enclosed in double quotation marks preceded by a backslash (\), as shown here:

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function : " \"1A\" + \"1B\" " ;

The absence of a backslash causes the quotation marks to terminate the function

statement.

The following function statements all describe 2-input multiplexers. The parentheses are

optional. The operators and operands are separated by spaces.

function : "A S + B S’" ;

function : "A & S | B & !S" ;

function : "(A * S) + (B * S’)" ;

Grouped Pins in a function Statement

Grouped pins can be used as variables in the function attribute statement.

In function attribute statements that use bus or bundle names, all the variables must be

either buses or bundles of the same width, or a single bus pin.

Ranges of buses or bundles are valid as long as the range you define contains the same

number of members (pins) as the other buses or bundles in the same expression. You can

reverse the bus order by listing the member numbers in reverse (high:low) order.

When the function attribute of a cell with group input pins is a combinational logic

function of grouped variables only, the logic function is expanded to apply to each set of

output grouped pins independently. For example, if A, B, and Z are defined as buses of the

same width and the function statement for output Z is

function : "(A & B)" ;

the function for Z[0] is interpreted as

function : "(A[0] & B[0])" ;

and the function for Z[1] is interpreted as

function : "(A[1] & B[1])" ;

If a bus and a single pin are in the same function attribute, the single pin is distributed

across all members of the bus. For example, if A and Z are buses of the same width, B is a

single pin, and the function statement for the Z output is

function : "(A & B)" ;

the function for Z[0] is interpreted as

function : "(A[0] & B)" ;

Likewise, the function for Z[1] is interpreted as

function : "(A[1] & B)" ;

has_builtin_pad Simple Attribute

Use this attribute in the case of an FPGA containing an ASIC core connected to the chip’s

port. When set to true, this attribute specifies that an output pin has a built-in pad, which

prevents pads from being inserted on the net connecting the pin to the chip’s port.

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Syntax

has_builtin_pad : Boolean ;

Example

has_builtin_pad : true ;

hysteresis Simple Attribute

The hysteresis attribute allows the pad to accommodate longer transition times, which

are more subject to noise problems.

Syntax

hysteresis : true | false ;

When the attribute is set to true, the vil and vol voltage ratings are actual transition points.

When the hysteresis attribute is omitted, the value is assumed to be false and no

hysteresis occurs.

Example

hysteresis : true ;

input_map Simple Attribute

The input_map attribute maps the input, internal, or output pin names to input and internal

node names defined in the statetable group.

Syntax

input_map : nameid ;

name

A string representing a name or a list of port names, separated by spaces,

that correspond to the input pin names, followed by the internal node

names.

Example

input_map : " D G R Q " ;

input_signal_level Simple Attribute

The input_signal_level attribute describes the voltage levels in the pin group of a

cell with multiple power supplies. If the input_signal_level or

output_signal_level attribute is missing, you can apply the default power supply

name to the cell.

Syntax

input_signal_level: nameid ;

output_signal_level: nameid ;

name

A string representing the name of the power supply already defined at the

library level. The input_signal_level attribute is used for an input or

inout pin definition. The output_signal_level attribute is used for an

output or inout pin definition.

Example

input_signal_level: VDD1 ;

output_signal_level: VDD2 ;

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input_threshold_pct_fall Simple Attribute

Use the input_threshold_pct_fall attribute to set the value of the threshold point on

an input pin signal falling from 1 to 0. You can specify this attribute at the library-level to set

a default value for all pins.

Syntax

input_threshold_pct_fall : trip_pointfloat ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the threshold

point of an input pin signal falling from 1 to 0. The default value is 50.0.

Example

input_threshold_pct_fall : 60.0 ;

input_threshold_pct_rise Simple Attribute

Use the input_threshold_pct_rise attribute to set the value of the threshold point on

an input pin signal rising from 0 to 1. You can specify this attribute at the library-level to set

a default value for all pins.

Syntax

input_threshold_pct_rise : trip_pointfloat ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the threshold

point of an input pin signal rising from 0 to 1. The default value is 50.0.

Example

input_threshold_pct_rise : 40.0 ;

input_voltage Simple Attribute

You can define a special set of voltage thresholds in the library group with the

input_voltage or output_voltage attribute. You can then apply the default voltage

ranges in the group to selected cells with the input_voltage or output_voltage

attribute in the pin definition.

Syntax

input_voltage : nameid ; ;

output_voltage : nameid ; ;

name

A string representing the name of the voltage range group defined at the

library level. The input_voltage attribute is used for an input pin

definition, and the output_voltage attribute is used for an output pin

definition.

Example

input_voltage : CMOS_SCHMITT ;

output_voltage : GENERAL ;

internal_node Simple Attribute

The internal_node attribute describes the sequential behavior of an internal pin or an

output pin. It indicates the relationship between an internal node in the statetable group

and a pin of a cell. Each output or internal pin with the internal_node attribute can also

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have the optional input_map attribute.

Syntax

internal_node : pin_nameid ;

pin_name

Name of either an internal or output pin.

Example

internal_node : IQ ;

inverted_output Simple Attribute

Except in statetable cells, where it is required, the inverted_output attribute is an

optional Boolean attribute that can be set for any output port. Set this attribute to true if the

output from the pin is inverted. Set it to false if the output is not inverted.

Syntax

inverted_output : Boolean expression ;

Example

inverted_output : true

is_pad Simple Attribute

The is_pad attribute indicates which pin represents the pad.

Syntax

is_pad : Boolean expression ;

This attribute must be used on at least one pin with a pad_cell attribute.

Example

cell(INBUF) {

...

pad_cell : true ;

...

pin(PAD) {

direction : input ;

is_pad : true ;

...

}

isolation_cell_enable_pin Simple Attribute

The isolation_cell_enable_pin attribute specifies the enable input pin on an

isolation cell. For more information about isolation cells, see “is_isolation_cell Simple

Attribute ” .

Syntax

isolation_cell_enable_pin : Boolean expression ;

Boolean expression

Valid values are true and false.

Example

isolation_cell_enable_pin : true ;

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level_shifter_enable_pin Simple Attribute

The level_shifter_enable_pin attribute specifies the enable input pin on a level

shifter cell. For more information about level shifter cells, see “is_level_shifter Simple

Attribute ” .

Syntax

level_shifter_enable_pin : Boolean expression ;

Boolean expression

Valid values are true and false.

Example

level_shifter_enable_pin : true ;

map_to_logic Simple Attribute

The map_to_logic attribute specifies which logic level to tie a pin to when a power gating

cell functions as a normal cell. For more information about power gating cells, see

“power_gating_cell Simple Attribute ” .

Syntax

map_to_logic : Boolean expression ;

Boolean expression

Valid values are 1 and 0.

Example

map_to_logic :1 ;

max_capacitance Simple Attribute

The max_capacitance attribute defines the maximum total capacitive load an output pin

can drive. Define this attribute only for an output or inout pin.

Syntax

max_capacitance : valuefloat ;

value

A floating-point number that represents the capacitive load.

Example

max_capacitance : 1 ;

max_fanout Simple Attribute

The max_fanout attribute defines the maximum fanout load that an output pin can drive.

Syntax

max_fanout : valuefloat ;

value

A floating-point number that represents the number of fanouts the pin can

drive. There are no fixed units for max_fanout. Typical units are standard

loads or pin count.

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Example

In the following example, pin X can drive a fanout load of no more than 11.0.

pin (X) {

direction : output ;

max_fanout : 11.0 ;

}

max_input_noise_width Simple Attribute

The max_input_noise_width attribute allows you to specify a maximum value for the

input noise width on an input pin or an output pin.

Note:

When you specify a max_input_noise_width value, you must also specify a

min_input_noise_width value that is less than or equal to the

max_input_noise_width value.

Syntax

max_input_noise_width : valuefloat ;

value

A floating-point number that represents the maximum input noise width.

Example

max_input_noise_width : 0.0 ;

max_transition Simple Attribute

The max_transition attribute defines a design rule constraint for the maximum

acceptable transition time of an input or output pin.

Syntax

max_transition : valuefloat ;

value

A floating-point number in units consistent with other time values in the

library.

Example

The following example shows a max_transition time of 4.2:

max_transition : 4.2 ;

min_capacitance Simple Attribute

The min_capacitance attribute defines the minimum total capacitive load an output pin

should drive. Define this attribute only for an output or inout pin.

Syntax

min_capacitance : valuefloat ;

value

A floating-point number that represents the capacitive load.

Example

min_capacitance : 1 ;

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min_fanout Simple Attribute

The min_fanout attribute defines the minimum fanout load that an output pin should drive.

Syntax

min_fanout : valuefloat ;

value

A floating-point number that represents the minimum number of fanouts the

pin can drive. There are no fixed units for min_fanout. Typical units are

standard loads or pin count.

Example

In the following example, pin X can drive a fanout load of no less than 3.0.

pin (X) {

direction : output ;

min_fanout : 3.0 ;

}

min_input_noise_width Simple Attribute

The min_input_noise_width attribute allows you to specify a minimum value for the

input noise width on an input pin or an output pin.

Note:

When you specify a min_input_noise_width value, you must also specify a

max_input_noise_width value that is equal to or greater than the

min_input_noise_width value.

Syntax

min_input_noise_width : valuefloat ;

value

A floating-point number that represents the minimum input noise width.

Example

min_input_noise_width : 0.0 ;

min_period Simple Attribute

Placed on the clock pin of a flip-flop or latch, the min_period attribute specifies the

minimum clock period required for the input pin.

Syntax

min_period : valuefloat ;

value

A floating-point number indicating a time unit.

Example

pin (CLK4) {

direction : input ;

capacitance : 1 ;

clock : true ;

min_period : 26.0 ;

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min_pulse_width_high Simple Attribute

The VHDL library generator uses the optional min_pulse_width_high and

min_pulse_width_low attributes for simulation.

Syntax

min_pulse_width_high : valuefloat ;

value

A floating-point number defined in units consistent with other time values in

the library. It gives the minimum length of time the pin must remain at logic

1 (min_pulse_width_high) or logic 0 (min_pulse_width_low).

Example

The following example shows both attributes on a clock pin, indicating the minimum pulse

width for a clock pin.

pin(CLK) {

direction : input ;

capacitance : 1 ;

min_pulse_width_high : 3 ;

min_pulse_width_low : 3 ;

}

min_pulse_width_low Simple Attribute

For information about using the min_pulse_width_high attribute, see the description of the

“min_pulse_width_high Simple Attribute ” .

multicell_pad_pin Simple Attribute

The multicell_pad_pin attribute indicates which pin on a cell should be connected to

another cell to create the correct configuration.

Syntax

multicell_pad_pin : true | false ;

Use this attribute for all pins on a pad cell or auxiliary pad cell that are connected to another

cell.

Example

multicell_pad_pin : true ;

nextstate_type Simple Attribute

In a pin group, the nextstate_type attribute defines the type of the next_state

attribute. You define a next_state attribute in an ff group or an ff_bank group.

Note:

Specify a nextstate_type attribute to ensure that the sync set (or sync reset) pin and

the D pin of sequential cells are not swapped when the design is instantiated.

Syntax

nextstate_type : data | preset

| clear | load | scan_in | scan_enable ;

where

data

Identifies the pin as a synchronous data pin. This is the default value.

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preset

Identifies the pin as a synchronous preset pin.

clear

Identifies the pin as a synchronous clear pin.

load

Identifies the pin as a synchronous load pin.

scan_in

Identifies the pin as a synchronous scan-in pin.

scan_enable

Identifies the pin as a synchronous scan-enable pin.

Any pin with the nextstate_type attribute must be in the next_state function. A

consistency check is also made between the pin’s nextstate_type attribute and the

next_state function. Format Example & Pagenot handled yet. shows a

nextstate_type attribute in a bundle group.

output_signal_level Simple Attribute

See “input_signal_level Simple Attribute ” .

output_voltage Simple Attribute

See “input_voltage Simple Attribute ” .

pg_function Simple Attribute

The pg_function attribute is used for the coarse-grain switch cells' virtual VDD output

pins to represent the propagated power level through the switch as a function of input

pg_pins. This is normally a logical buffer and is useful in cases where the VDD and VSS

connectivity may be erroneously reversed.

Syntax

pg_function : "<function_string>" ;

Example

pg_function : "VDD" ;

pin_func_type Simple Attribute

The pin_func_type attribute describes the functionality of a pin.

Syntax

pin_func_type : clock_enable | active_high | active_low |

active_rising | active_falling ;

clock_enable

Enables the clocking mechanism.

active_high and active_low

Describes the clock active edge or the level of the enable pin of the latches.

active_rising and active_falling

Describes the clock active edge or level of the clock pin of the flip-flops.

Example

pin_func_type : clock_enable ;

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power_down_function Simple Attribute

The power_down_function string attribute is used to identify the condition when an

output pin is switched off by pg_pin and to specify the Boolean condition under which the

cell’s output pin is switched off (when the cell is in "off" mode due to the external power pin

states).

If the power_down_function is "1" then X is assumed on the pin.

Syntax

power_down_function : function_string ;

Example

power_down_function : "!VDD + VSS";

prefer_tied Simple Attribute

The prefer_tied attribute describes an input pin of a flip-flop or latch. It indicates what

the library developer wants this pin connected to.

Syntax

prefer_tied : "0" | "1" ;

You can have as many prefer_tied attributes as possible while it is still able to

implement D functionality.However, not all will be honored.

For example, if the library developer specifies

prefer_tied : "0" ;

on all the inputs, as many as possible are honored and the rest are ignored. If they are

ignored, a message indicating this fact is issued during execution of the read_lib

command.

Example

The following example shows a prefer_tied attribute on a test-enable pin.

pin(TE) {

direction : input;

prefer_tied : "0" ;

}

primary_output Simple Attribute

The primary_output attribute describes the primary output pin of a device that has more

than one output pin for a particular phase of the output signal. When set to true, it indicates

that one of the output pins is the primary output pin.

Syntax

primary_output : true | false ;

pulling_current Simple Attribute

The pulling_current attribute defines the current-drawing capability of a pull-up or pull-

down device on a pin. This attribute can be used for pins with the driver_type attribute

set to pull_up or pull_down.

Syntax

pulling_current : current value ;

current value

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If you characterize your pull-up or pull-down devices in terms of the current

drawn during nominal operating conditions, use pulling_current

instead of pulling_resistance.

Example

pin(Y) {

direction : output ;

driver_type : pull_up ;

pulling_resistance : 1000 ;

...

}

pulling_resistance Simple Attribute

The pulling_resistance attribute defines the resistance strength of a pull-up or pull-

down device on a pin. This attribute can be used for pins with the driver_type attribute

set to pull_up or pull_down.

Syntax

pulling_resistance : resistance value ;

resistance value

The resistive strength of the pull-up or pull-down device.

Example

pin(Y) {

direction : output ;

driver_type : pull_up ;

pulling_resistance : 1000 ;

...

}

pulse_clock Simple Attribute

Use the pulse_clock attribute to model edge-derived clocks at the pin level.

Syntax

pulse_clock : pulse_typeenum ;

pulse_type

The valid values are rise_triggered_high_pulse,

rise_triggered_low_pulse, fall_triggered_high_pulse, and

fall_triggered_low_pulse.

Example

pin(Y) {

...

pulse_clock : rise_triggered_low_pulse ;

...

}

related_ground_pin Simple Attribute

The optional related_power_pin and related_ground_pin attributes, defined at the

pin level for output pins and inout pins, replace the output_signal_level attribute.

These attributes can also be defined at the pin level for input/inout pins to replace the

input_signal_level, except when you have input overdrive models. In this case, you

need to use the input_signal_level to capture the input overdrive voltage, which

cannot be modeled with related_power_pin. In power and ground pin syntax, the

pg_pin groups are mandatory for each cell, and a cell must have at least one

primary_power pg_pin and at least one primary_ground pg_pin. Therefore, the

default related_power_pin and related_ground_pin of a cell will always exist.

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Syntax

related_ground_pin : pg_pin_nameid ;

pg_pin_name

Name of the related ground pin.

Example

pin(Y) {

...

related_ground_pin : G1 ;

...

}

related_power_pin Simple Attribute

For details about the related_ground_pin attribute, see “related_ground_pin Simple

Attribute” .

Syntax

related_power_pin : pg_pin_nameid ;

pg_pin_name

Name of the related power pin.

Example

pin(Y) {

...

related_power_pin : P1 ;

...

}

rise_capacitance Simple Attribute

Defines the load for an input or an inout pin when its signal is rising.

Setting a value for the rise_capacitance attribute requires that a value for

fall_capacitance attribute also be set, and setting a value for fall_capacitance

requires that a value for the rise_capacitance also be set.

Syntax

rise_capacitance : float ;

float

A floating-point number in units consistent with other capacitance

specifications throughout the library. Typical units of measure for

rise_capacitance include picofarads and standardized loads.

Example

The following example defines the A and B pins in an AND cell, each with a

fall_capacitance of one unit, a rise_capacitance of two units, and a

capacitance of two units.

cell (AND) {

area : 3 ;

vhdl_name : "AND2" ;

pin (A,B) {

direction : input ;

fall_capacitance : 1 ;

rise_capacitance : 2 ;

capacitance : 2 ;

}

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rise_current_slope_after_threshold Simple Attribute

The rise_current_slope_after_threshold attribute represents a linear

approximation of the change in current over time from the point at which the rising transition

reaches the threshold to the end of the transition.

Syntax

rise_current_slope_after_threshold : valuefloat ;

value

A negative floating-point number that represents the change in current.

Example

rise_current_slope_after_threshold : -0.09 ;

rise_current_slope_before_threshold Simple Attribute

The rise_current_slope_before_threshold attribute represents a linear

approximation of the change in current over time, from the beginning of the rising transition

to the threshold point.

Syntax

rise_current_slope_before_threshold : valuefloat ;

value

A positive floating-point number that represents the change in current.

Example

rise_current_slope_before_threshold : 0.18;

rise_time_after_threshold Simple Attribute

The rise_time_after_threshold attribute gives the time interval from the threshold

point of the rising transition to the end of the transition.

Syntax

rise_time_after_threshold : valuefloat ;

value

A floating-point number that represents the time interval for the rise

transition from threshold to finish (after).

Example

rise_time_after_threshold : 2.4;

rise_time_before_threshold Simple Attribute

The rise_time_before_threshold attribute gives the time interval from the beginning

of the rising transition to the point at which the threshold is reached.

Syntax

rise_time_before_threshold : valuefloat ;

value

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A floating-point number that represents the time interval for the rise

transition from start to threshold (before).

Example

rise_time_before_threshold : 0.8 ;

signal_type Simple Attribute

In a test_cell group, signal_type identifies the type of test pin.

Syntax

signal_type : test_scan_in | test_scan_in_inverted

|

test_scan_out | test_scan_out_inverted |

test_scan_enable |

test_scan_enable_inverted |

test_scan_clock | test_scan_clock_a |

test_scan_clock_b | test_clock ;

test_scan_in

Identifies the scan-in pin of a scan cell. The scanned value is the same as

the value present on the scan-in pin. All scan cells must have a pin with

either the test_scan_in or the test_scan_in_inverted attribute.

test_scan_in_inverted

Identifies the scan-in pin of a scan cell as having inverted polarity. The

scanned value is the inverse of the value present on the scan-in pin.

For multiplexed flip-flop scan cells, the polarity of the scan-in pin is inferred

from the latch or ff declaration of the cell itself. For other types of scan

cells, clocked-scan, LSSD, and multiplexed flip-flop latches, it is not

possible to give the ff or latch declaration of the entire scan cell. For these

cases, you can use the test_scan_in_inverted attribute in the cell

where the scan-in pin appears in the latch or ff declarations for the entire

cell.

test_scan_out

Identifies the scan-out pin of a scan cell. The value present on the scan-out

pin is the same as the scanned value. All scan cells must have a pin with

either a test_scan_out or a test_scan_out_inverted attribute.

The scan-out pin corresponds to the output of the slave latch in the LSSD

methodologies.

test_scan_out_inverted

Identifies the scan-out pin of a test cell as having inverted polarity. The

value on this pin is the inverse of the scanned value.

test_scan_enable

Identifies the pin of a scan cell that, when high, indicates that the cell is

configured in scan-shift mode. In this mode, the clock transfers data from

the scan-in input to the scan-out input.

test_scan_enable_inverted

Identifies the pin of a scan cell that, when low, indicates that the cell is

configured in scan-shift mode. In this mode, the clock transfers data from

the scan-in input to the scan-out input.

test_scan_clock

Identifies the test scan clock for the clocked-scan methodology. The signal

is assumed to be edge-sensitive. The active edge transfers data from the

scan-in pin to the scan-out pin of a cell. The sense of this clock is

determined by the sense of the associated timing arcs.

test_scan_clock_a

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Identifies the a clock pin in a cell that supports a single-latch LSSD, double-

latch LSSD, clocked LSSD, or auxiliary clock LSSD methodology. When

the a clock is at the active level, the master latch of the scan cell can

accept scan-in data. The sense of this clock is determined by the sense of

the associated timing arcs.

test_scan_clock_b

Identifies the b clock pin in a cell that supports the single-latch LSSD,

clocked LSSD, or auxiliary clock LSSD methodology. When the b clock is

at the active level, the slave latch of the scan-cell can accept the value of

the master latch. The sense of this clock is determined by the sense of the

associated timing arcs.

test_clock

Identifies an edge-sensitive clock pin that controls the capturing of data to

fill scan-in test mode in the auxiliary clock LSSD methodology.

If an input pin is used in both test and nontest modes (such as the clock input in the

multiplexed flip-flop methodology), do not include a signal_type statement for that pin in

the test_cell pin definition.

If an input pin is used only in test mode and does not exist on the cell that it will scan and

replace, you must include a signal_type statement for that pin in the test_cell pin

definition.

If an output pin is used in nontest mode, it needs a function statement. The

signal_type statement is used to identify an output pin as a scan-out pin. In a

test_cell group, the pin group for an output pin can contain a function statement, a

signal_type attribute, or both.

Note:

You do not have to define a function or signal_type attribute in the pin group if the

pin is defined in a previous test_cell group for the same cell.

Example

signal_type : test_scan_in ;

slew_control Simple Attribute

The slew_control attribute provides increasing levels of slew-rate control to slow down

the transition rate. This attribute associates a coarse measurement of slew-rate control with

the output pad cell.

Syntax

slew_control : low | medium | high | none ;

low, medium, high

Provides increasingly higher levels of slew-rate control.

none

Indicates that no slew-rate control is applied. If you do not use

slew_control, none is the default.

This attribute limits peak noise by smoothing out fast output transitions, thus decreasing the

possibility of a momentary disruption in the power or ground planes.

slew_lower_threshold_pct_fall Simple Attribute

Use the slew_lower_threshold_pct_fall attribute to set the value of the lower

threshold point used in modeling the delay of a pin falling from 1 to 0. You can specify this

attribute at the library-level to set a default value for all pins.

Syntax

slew_lower_threshold_pct_fall : trip_pointvalue ;

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trip_point

A floating-point number between 0.0 and 100.0 that specifies the lower

threshold point used to model the delay of a pin falling from 1 to 0. The

default value is 20.0.

Example

slew_lower_threshold_pct_fall : 30.0 ;

slew_lower_threshold_pct_rise Simple Attribute

Use the slew_lower_threshold_pct_rise attribute to set the value of the lower

threshold point used in modeling the delay of a pin rising from 0 to 1. You can specify this

attribute at the library-level to set a default value for all pins.

Syntax

slew_lower_threshold_pct_rise : trip_pointvalue ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the lower

threshold point used to model the delay of a pin rising from 0 to 1. The

default value is 20.0.

Example

slew_lower_threshold_pct_rise : 30.0 ;

slew_upper_threshold_pct_fall Simple Attribute

Use the slew_upper_threshold_pct_fall attribute to set the value of the upper

threshold point uses in modeling the delay of a pin falling from 1 to 0. You can specify this

attribute at the library-level to set a default value for all pins.

Syntax

slew_upper_threshold_pct_fall : trip_pointvalue ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the upper

threshold pointused to model the delay of a pin falling from 1 to 0. The

default value is 80.0.

Example

slew_upper_threshold_pct_fall : 70.0 ;

slew_upper_threshold_pct_rise Simple Attribute

Use the slew_upper_threshold_pct_rise attribute to set the value of the upper

threshold pointused in modeling the delay of a pin rising from 0 to 1. You can specify this

attribute at the library-level to set a default value for all pins.

Syntax

slew_upper_threshold_pct_rise : trip_pointvalue ;

trip_point

A floating-point number between 0.0 and 100.0 that specifies the upper

threshold pointused to model the delay of a pin rising from 0 to 1. The

default value is 80.0.

Example

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slew_upper_threshold_pct_rise : 70.0 ;

state_function Simple Attribute

The state_function attribute defines output logic. The attribute describes a function of

input and inout ports that can be made three-state, or ports with an internal_node

attribute. A port in the state_function expression refers only to the non-three-state

functional behavior of that port. An inout port in the state_function expression is

treated only as an input port.

Syntax

state_function : "Boolean expression" ;

Example

state_function : "QN’" ;

For a list of Boolean operators, see Table 3-2.

std_cell_main_rail Simple Attribute

The std_cell_main_rail Boolean attribute is defined in a primary_power power pin.

When the attribute is set to true, the power and ground pin is used to determine which side

of the voltage boundary the power and ground pin is connected.

Syntax

std_cell_main_rail : true | false ;

Example

std_cell_main_rail : true ;

switch_function Simple Attribute

The switch_function string attribute identifies the condition when the attached design

partition is turned off by the input switch_pin.

For a coarse-grain switch cell, the switch_function attribute can be defined at both

controlled power and ground pins (virtual VDD and virtual VSS for pg_pin) and the output

pins.

When the switch_function attribute is defined in the controlled power and ground pin, it

is used to specify the Boolean condition under which the cell switches off (or drives a Z to)

the controlled design partitions, including the traditional signal input pins only (with no

related power pins to this output).

Syntax

switch_function : function_string ;

Example

switch_function : "CTL";

switch_pin Simple Attribute

The switch_pin attribute is a pin-level Boolean attribute. When it is set to true, it is used

to identify the pin as the switch pin of a coarse-grain switch cell.

Syntax

switch_pin : valueBoolean ;

Example

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switch_pin : true ;

test_output_only Simple Attribute

This attribute can be set for any output port described in statetable format.

In ff/latch format, if a port is to be used for both function and test, you provide the functional

description using the function attribute. If a port is to be used for test only, you omit the

function attribute.

In statetable format, however, a port always has a functional description. Therefore, if you

want to specify that a port is for test only, you set the test_output_only attribute to true.

Syntax

test_output_only : true | false ;

Example

pin (scout) {

direction : output ;

signal_type : test_scan_out ;

test_output_only : true ;

}

three_state Simple Attribute

The three_state attribute defines a three-state output pin in a cell.

Syntax

three_state : "Boolean expression" ;

Boolean expression

An equation defining the condition that causes the pin to go to the high-

impedance state. The syntax of this equation is the same as the syntax of

the function attribute statement described in “function Simple Attribute ” .

The three_state attribute can be used in both combinational and

sequential pin groups, with bus or bundle variables.

Example

three_state : "!E" ;

For a list of Boolean operators, see Table 3-2.

vhdl_name Simple Attribute

The vhdl_name attribute defines valid VHDL object names. In cell and pin groups, use

vhdl_name to resolve conflicts of invalid object names when porting from .db to VHDL.

Some .db object names might violate the more restrictive VHDL rules for identifiers.

Syntax

vhdl_name : "namestring" ;

name

A string that represents a valid VHDL object name.

Example

vhdl_name : "INb" ;

Example 3-4 shows a vhdl_name attribute in a cell group.

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Example 3-4 Use of the vhdl_name Attribute in a Cell Description

cell (INV) {

area : 1;

pin(IN) {

vhdl_name : "INb";

direction : input;

capacitance : 1;

}

pin(Z) {

direction : output;

function : "IN’";

timing () {

intrinsic_rise : 0.23;

intrinsic_fall : 0.28;

rise_resistance : 0.13;

fall_resistance : 0.07;

related_pin : "IN";

}

x_function Simple Attribute

The x_function attribute describes the X behavior of an output or inout pin. X is a state

other than 0, 1, or Z.

Syntax

x_function : "Boolean expression" ;

Example

x_function : "!an * ap" ;

3.1.3 Complex Attributes

This section describes the complex attributes you can use in a pin group.

fall_capacitance_range Complex Attribute

The fall_capacitance_range attribute specifies a range of values for pin capacitance

during fall transitions.

Syntax

fall_capacitance_range (value_1float, value_2float) ;

value_1, value_2

Positive floating-point numbers that specify the range of values.

Example

fall_capacitance_range (0.0, 0.0) ;

power_gating_pin Complex Attribute

Note:

The power_gating_pin attribute has been replaced by the

retention_pin attribute. See “retention_pin Complex Attribute” .

The power_gating_pin attribute specifies a pair of pin values for a power gating cell.

The first value represents the power gating pin class. The second value specifies which

logic level (default) the power gating cell is tied to when the power gating cell is functioning

in normal mode. For more information about specifying power gating cells, see

“power_gating_cell Simple Attribute ” .

Syntax

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power-gating_pin ("value_1enum", value_2Boolean) ;

value_1

A string that represents one of five predefined classes of power gating

pins: power_pin_[1-5].

value_2

An integer that specifes the default logic level for the pin when the power

gating cell functions as a normal cell.

Example

power_gating_pin ( "power_pin_1", 0) ;

retention_pin Complex Attribute

The retention_pin complex attribute identifies the retention pins of a retention cell. The

attribute defines the following information:

● pin class

Valid values:

❍ restore

Restores the state of the cell.

❍ save

Saves the state of the cell.

❍ save_restore

Saves and restores the state of the cell.

● disable value

Defines the value of the retention pin when the cell works in normal mode. The

valid values are 0 and 1.

Syntax

retention_pin (pin_class, disable_value) ;

Example

retention_pin (power_pin_1, 0) ;

rise_capacitance_range Complex Attribute

The rise_capacitance_range attribute specifies a range of values for pin capacitance

during rise transitions.

Syntax

rise_capacitance_range (value_1float, value_2float) ;

value_1, value_2

Positive floating-point numbers that specify the range of values.

Example

rise_capacitance_range (0.0, 0.0) ;

3.2 Group Statements

You can use the following group statements in a pin group:

ccsn_first_stage () {}

ccsn_last_stage () {}

dc_current () {}

electromigration () { }

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hyperbolic_noise_above_high () { }

hyperbolic_noise_below_low () { }

hyperbolic_noise_high () { }

hyperbolic_noise_low () { }

input_signal_swing () {}

internal_power () { }

max_capacitance () { }

max_transition () { }

min_pulse_width () { }

minimum_period () { }

output_signal_swing () {}

pin_capacitance() { }

timing () { }

tlatch () { }

3.2.1 ccsn_first_stage Group

Use the ccsn_first_stage group to specify CCS noise for the first stage of the channel-

connected block (CCB).

A ccsn_first_stage or ccsn_last_stage group contains the following information:

● A set of CCB parameters: is_needed, is_inverting, stage_type,

miller_cap_rise, and miller_cap_fall

● A two-dimensional DC current table: dc_current group

● Two timing tables for rising and falling transitions: output_current_rise

group, output_current_fall group

● Two noise tables for low and high propagated noise: propagated_noise_low

group, propagated_noise_high group

Note that if the ccsn_first_stage and ccsn_last_stage groups are defined inside

pin-level groups, then the ccsn_first_stage group can only be defined in an input pin

or an inout pin, and the ccsn_last_stage group can only be defined in an output pin or

an inout pin.

Syntax

library (name) {

...

cell (name) {

pin (name) {

...

ccsn_first_stage () {

is_needed : <boolean>;

is_inverting : <boolean>;

stage_type : <stage_type_value>;

miller_cap_rise : <float>;

miller_cap_fall : <float>;

dc_current (<dc_current_template>)

index_1("<float>, ...");

index_2("<float>, ...");

values("<float>, ...");

}

output_voltage_rise ( )

vector (<output_voltage_template_name>) {

index_1(<float>);

index_2(<float>);

index_3("<float>, ...");

values("<float>, ...");

}

...

}

output_voltage_fall ( ) {

vector (<output_voltage_template_name>) {

index_1(<float>);

index_2(<float>);

index_3("<float>, ...");

values("<float>, ...");

}

...

}

propagated_noise_low ( ) {

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vector (<propagated_noise_template_name>) {

index_1(<float>);

index_2(<float>);

index_3(<float>);

index_4("<float>, ...");

values("<float>, ...");

}

...

}

propagated_noise_high ( ) {

vector (<propagated_noise_template_name>) {

index_1(<float>);

index_2(<float>);

index_3(<float>);

index_4("<float>, ...");

values("<float>, ...");

}

...

}

when : <boolean expression>;

}

Simple Attributes

is_inverting

is_needed

miller_cap_fall

miller_cap_rise

stage_type

when

Group Statements

dc_current

output_voltage_fall

output_voltage_rise

propagated_noise_low

propagated_noise_rise

is_inverting Simple Attribute

Use the is_inverting attribute to specify whether the channel-connecting block is

inverting. This attribute is mandatory if the is_needed attribute value is true. If the channel-

connecting block is inverting, set the attribute to true. Otherwise, set the attribute to false.

Note that this attribute is different from the “invertness” (or timing_sense) of a timing arc,

which may consist of multiple channel-connecting blocks.

Syntax

is_inverting : valueBoolean ;

value

Valid values are true and false . Set the value to true when the channel-

connecting block is inverting.

Example

is_inverting : true ;

is_needed Simple Attribute

Use the is_needed attribute to specify whether composite current source (CCS) noise

modeling data is required.

Syntax

is_needed : valueBoolean ;

value

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Valid values are true and false . The default is true. Set the value to false

for cells such as diodes, antennas, and cload cells that do not need current-

based data.

Example

is_needed : true ;

miller_cap_fall Simple Attribute

Use the miller_cap_fall attribute to specify the Miller capacitance value for the

channel-connecting block.

Syntax

miller_cap_fall : valuefloat ;

value

A floating-point number representing the Miller capacitance value. The

value must be greater or equal to zero.

Example

miller_cap_fall : 0.00084 ;

miller_cap_rise Simple Attribute

Use the miller_cap_rise attribute to specify the Miller capacitance value for the

channel-connecting block.

Syntax

miller_cap_rise : valuefloat ;

value

A floating-point number representing the Miller capacitance value. The

value must be greater or equal to zero.

Example

miller_cap_rise : 0.00055 ;

stage_type Simple Attribute

Use the stage_type attribute to specify the stage type of the channel-connecting block

output voltage.

Syntax

stage_type : valueenum ;

value

The valid values are pull_up,in which the output voltage of the channel-

connecting block is always pulled up (rising); pull_down, in which the

output voltage of the channel-connecting block is always pulled down

(falling); and both, in which the output voltage of the channel-connecting

block is pulled up or down.

Example

stage_type : pull_up ;

when Simple Attribute

The when attribute is defined in both the pin-level and the timing-level

ccsn_first_stage and ccsn_last_stage groups. Use this attribute to specify the

condition under which the channel-connecting block data is applied.

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Syntax

when : valueboolean ;

value

Result of a Boolean expression.

dc_current Group

Use the dc_current group to specify the input and output voltage values of a two-

dimensional current table for a channel-connecting block.

Syntax

dc_current( dc_current_templateid ) { }

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

values ("float, ..., float") ;

dc_current_template

The name of the dc current lookup table.

Use index_1 to represent the input voltage and index_2 to represent the output voltage.

The values attribute of the group lists the relative channel-connecting block dc current

values in library units measured at the channel-connecting block output node.

output_voltage_fall Group

Use the output_voltage_fall group to specify vector groups that describe three-

dimensional output_voltage tables of the channel-connecting block whose output

node’s voltage values are falling.

output_voltage_fall ( ) {

vector (<output_voltage_template_name>) {

index_1(float);

index_2(float);

index_3("float, ...");

values("float, ...");

Complex Attributes

index_1

index_2

index_3

values

The index_1 attribute of the vector group lists the input_net_transition (slew)

values, in library “time” units, of the channel-connecting block.The index_2 attribute of the

vector group lists the total_output_net_capacitance (load) values, in library

“capacitance” units, of the channel-connecting block.The index_3 attribute of the vector

group lists the sampling time values, in library “time” units, of the channel-connecting block.

The values attribute of the vector group list the voltage values, in library “voltage” units,

measured at the channel-connecting block output node.

output_voltage_rise Group

Use the output_voltage_rise group to specify vector groups that describe three-

dimensional output_voltage tables of the channel-connecting block whose output

node’s voltage values are raising.

For details, see the output_voltage_fall group description.

propogated_noise_high Group

The propagated_noise_high group uses vector groups to specify the three-

dimensional output_voltage tables of the channel-connecting block whose output

node’s voltage values are rising.

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propagated_noise_high ( ) {

vector (<output_voltage_template_name>) {

index_1(float);

index_2(float);

index_3(float);

index_4(“float, ...");

values("float, ...");

Complex Attributes

index_1

index_2

index_3

index_4

values

The index_1 attribute of the vector group lists the input_noise_height values, in

library “voltage” units, of the channel-connecting block.The index_2 attribute of the vector

group lists the input_noise_width values, in library “time” units, of the channel-

connecting block.The index_3 attribute of the vector group lists the

total_output_net_capacitance values, in library “capacitance” units, of the channel-

connecting block.The index_4 attribute of the vector group lists the sampling time values,

in library “time” units, of the channel-connecting block.The values attribute of the vector

group list the voltage values, in library “voltage” units, measured at the channel-connecting

block output node.

propogated_noise_low Group

Use the propagated_noise_low group to specify the three-dimensional

output_voltage tables of the channel-connecting block whose output node’s voltage

values are falling.

For details, see the “propogated_noise_high Group” .

3.2.2 ccsn_last_stage Group

Use the ccsn_last_stage group to specify composite current source (CCS) noise for the

last stage of the channel-connecting block.

For details, see “ccsn_first_stage Group” .

3.2.3 electromigration Group

An electromigration group is defined in a pin group, as shown here:

library (name) {

cell (name) {

pin (name) {

electromigration () {

... electromigration description ...

}

Simple Attributes

related_pin : "name | name_list" ;/* path dependency */

related_bus_pins : "list of pins" ;/* list of pin names */

when : Boolean expression ;

Complex Attributes

index_1 ("float, ..., float") ; /* optional */

index_2 ("float, ..., float") ; /* optional */

values ("float, ..., float") ;

Group Statement

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em_max_toggle_rate (em_template_name) {}

related_pin Simple Attribute

The related_pin attribute associates the electromigration group with a specific

input pin. The input pin’s input transition time is used as a variable in the electromigration

lookup table.

If more than one input pin is specified in this attribute, the weighted input transition time of

all input pins specified is used to index the electromigration table.

The pin or pins in the related_pin attribute denote the path dependency for the

electromigration group. A particular electromigration group is accessed if the

input pin or pins named in the related_pin attribute cause the corresponding output pin

named in the pin group to toggle. All functionally related pins must be specified in a

related_pin attribute if you specify two-dimensional tables.

Syntax

related_pin : "name | name_list"

name | name_list

Name of input pin or pins.

Example

related_pin : "A B" ;

related_bus_pins Simple Attribute

The related_bus_pins attribute associates the electromigration group with the

input pin or pins of a specific bus group. The input pin’s input transition time is used as a

variable in the electromigration lookup table.

If more than one input pin is specified in this attribute, the weighted input transition time of

all input pins specified is used to index the electromigration table.

Syntax

related_bus_pins : "name1 [name2 name3 ... ] " ;

Example

related_bus_pins : "A" ;

The pin or pins in the related_bus_pins attribute denote the path dependency for the

electromigration group. A particular electromigration group is accessed if the

input pin or pins named in the related_bus_pins attribute cause the corresponding

output pin named in the pin group to toggle. All functionally related pins must be specified

in a related_bus_pins attribute if two-dimensional tables are being used.

when Simple Attribute

The when attribute defines the enabling condition for the check in Synopsys logic

expression format.

Syntax

when : "Boolean expression" ;

Boolean expression

A Synopsys logic expression.

For a list of Boolean operators, see Table 3-3.

Example

when : "SE" ;

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index_1 and index_2 Complex Attributes

You can use the index_1 optional attribute to specify the breakpoints of the first dimension

of an electromigration table used to characterize cells for electromigration within the library.

You can use the index_2 optional attribute to specify breakpoints of the second dimension

of an electromigration table used to characterize cells for electromigration within the library.

You can overwrite the values entered for the em_lut_template group’s index_1 by

entering a value for the em_max_toggle_rate group’s index_1. You can overwrite the

value entered for the em_lut_template group’s index_2 by entering a value for the

em_max_toggle_rate group’s index_2.

Syntax

index_1 ("float, ..., float") ; /* optional */

index_2 ("float, ..., float") ; /* optional */

float

For index_1, the floating-point numbers that specify the breakpoints of

the first dimension of the electromigration table used to characterize cells

for electromigration within the library. For index_2, the floating-point

numbers that specify the breakpoints for the second dimension of the

electromigration table used to characterize cells for electromigration within

the library.

Example

index_1 ("0.0, 5.0, 20.0") ;

index_2 ("0.0, 1.0, 2.0") ;

values Complex Attribute

You use this complex attribute to specify the nets’ maximum toggle rates.

Syntax

values : ("float, ..., float") ;

float

Floating-point numbers that specify the net’s maximum toggle rates. The

number can be a list of nindex_1 positive floating-point numbers if the

table is one-dimensional and can be nindex_1 X nindex_2 positive

floating-point numbers if the table is two-dimensional, where nindex_1 is

the size of index_1 and nindex_2 is the size of index_2, specified for

these two indexes in the em_max_toggle_rate group or in the

em_lut_template group.

Example (One-Dimensional Table)

values : ("1.5, 1.0, 0.5") ;

Example (Two-Dimensional Table)

values : ("2.0, 1.0, 0.5", "1.5, 0.75, 0.33","1.0, 0.5, 0.15",) ;

em_max_toggle_rate Group

The em_max_toggle_rate group is a pin-level group that is defined within the

electromigration group.

library (name) {

cell (name) {

pin (name) {

electromigration () {

em_max_toggle_rate(em_template_name) {

... em_max_toggle_rate description...

}

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}

3.2.4 hyperbolic_noise_above_high Group

This optional group describes a noise immunity region as a hyperbolic curve when the input

is high and the noise is over the high voltage rail.

You specify a hyperbolic_noise_above_high group in a pin group, as shown here:

library (name) {

cell (name) {

pin (name) {

direction : input | inout ;

hyperbolic_noise_above_high () {

... hyperbola form description ...

}

Simple Attributes

area_coefficient

height_coefficient

width_coefficient

area_coefficient Simple Attribute

The area_coefficient attribute specifies the area coefficient used to describe a noise

immunity curve in hyperbola form.

Syntax

area_coefficient: valuefloat ;

value

A positive floating-point number. The unit is calculated as the library unit of

voltage times the library unit of time.

Example

area_coefficient : 1.1 ;

height_coefficient Simple Attribute

The height_coefficient attribute specifies the height coefficient used to describe a

noise immunity curve in hyperbola form.

Syntax

height_coefficient: valuefloat ;

value

A positive floating-point number. The unit is the library unit of voltage.

Example

height_coefficient : 0.4 ;

width_coefficient Simple Attribute

The width_coefficient attribute specifies the width coefficient used to describe a noise

immunity curve in hyperbola form.

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Syntax

width_coefficient: valuefloat ;

value

A positive floating-point number. The unit is the library unit of time.

Example

width_coefficient : 0.01 ;

Example

hyperbolic_noise_above_high () {

area_coefficient : 1.1 ;

height_coefficient : 0.4 ;

width_coefficient : 0.01 ;

}

3.2.5 hyperbolic_noise_below_low Group

This optional group describes a noise immunity region as a hyperbolic curve when the input

is low and the noise is below the low voltage rail.

For information about the group syntax and attributes, see “hyperbolic_noise_above_high

Group” .

3.2.6 hyperbolic_noise_high Group

This optional group describes a noise immunity region as a hyperbolic curve when the input

is high and the noise is below the high voltage rail

For information about the group syntax and attributes, see “hyperbolic_noise_above_high

Group” .

3.2.7 hyperbolic_noise_low Group

This optional group describes a noise immunity region as a hyperbolic curve when the input

is low and the noise is over the low voltage rail.

For information about the group syntax and attributes, see “hyperbolic_noise_above_high

Group” .

3.2.8 internal_power Group

An internal_power group is defined in a pin group, as shown here:

library (name) {

cell (name) {

pin (name) {

internal_power () {

... internal power description ...

}

Simple Attributes

equal_or_opposite_output

falling_together_group

power_level

related_pin

rising_together_group

switching_interval

switching_together_group

when

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Group Statements

domain

fall_power (template name) {}

power (template name) {}

rise_power (template name) {}

Syntax for One-Dimensional, Two-Dimensional, and Three-Dimensional Tables

You can define a one-, two-, or three-dimensional table in the internal_power group in

either of the following three ways:

● Using the power group

● Using a combination of the related_pin attribute, the fall_power group,

and the rise_power group

● Using a combination of the related_pin attribute, the power group, and the

equal_or_opposite attribute.

This is the syntax for a one-dimensional table using the power group:

internal_power() {

power (template name) {

values ("float, ..., float") ;

}

This is the syntax for a one-dimensional table using fall_power, and rise_power:

internal_power() {

fall_power (template name) {

values ("float, ..., float");

}

rise_power (template name) {

values ("float, ..., float");

}

This is the syntax for a two-dimensional table using the power group:

internal_power() {

power (template name) {

values ("float, ..., float");

}

This is the syntax for a two-dimensional table using the related_pin attribute and the

fall_power and rise_power groups:

internal_power() {

related_pin : "name | name_list" ;

fall_power (template name) {

values ("float, ..., float");

}

rise_power (template name) {

values ("float, ..., float");

}

This is the syntax for a three-dimensional table using the power group:

internal_power() {

power (template name) {

values ("float, ..., float");

}

This is the syntax for a three-dimensional table using the related_pin attribute, power

group, and the equal_or_opposite attribute:

internal_power() {

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related_pin : "name | name_list" ;

power (template name) {

values ("float, ..., float");

}

equal_or_opposite_output : "name | name_list" ;

}

equal_or_opposite_output Simple Attribute

The equal_or_opposite_output attribute designates optional output pin or pins whose

capacitance is used to access a three-dimensional table in the internal_power group.

Syntax

equal_or_opposite_output : "name | name_list" ;

name | name_list

The name of the output pin or pins.

Note:

This pin (or pins) has to be functionally equal to or opposite of the pin

named in this pin group.

Example

equal_or_opposite_output : "Q" ;

Note:

The output capacitance of this pin (or pins) is used as the total

output2_net_capacitance variable in the internal power lookup table.

falling_together_group Simple Attribute

The falling_together_group attribute identifies the list of two or more input or output

pins that share logic and are falling together during the same time period. This time period

is set with the switching_interval attribute; see “switching_interval Simple Attribute”

for details.

Together, the falling_together_group and switching_interval attribute settings

determine the level of power consumption.

Syntax

falling_together_group : "list of pins" ;

list of pins

The names of the input or output pins that share logic and are falling during

the same time period.

Example

cell (foo) {

pin (A) {

internal_power () {

falling_together_group : "B C D" ;

rising_together_group : "E F G" ;

switching_interval : 10.0 ;

rise_power () {

...

}

fall_power () {

...

}

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power_level Simple Attribute

This optional attribute is used for multiple power supply modeling. In the internal_power

group at the pin level, you can specify the power level used to characterize the lookup table.

Syntax

power_level : "name" ;

name

Name of the power rail defined in the power supply group.

Example

power_level : "VDD1" ;

related_pin Simple Attribute

This attribute is used only in three-dimensional tables. It associates the internal_power

group with a specific input or output pin. If related_pin is an output pin, it must be

functionally equal to or opposite of the pin in that pin group.

If related_pin is an input pin, the pin’s input transition time is used as a variable in the

internal power lookup table.

If related_pin is an output pin, the pin’s capacitance is used as a variable in the internal

power lookup table.

Syntax

related_pin : "name | name_list" ;

name | name_list

The name of the input or output pin or pins.

Example

related_pin : "A B" ;

The pin or pins in the related_pin attribute denote the path dependency for the

internal_power group. A particular internal_power group is accessed if the input pin

or pins named in the related_pin attribute cause the corresponding output pin named in

the pin group to toggle. All functionally related pins must be specified in a related_pin

attribute if two-dimensional tables are being used.

rising_together_group Simple Attribute

The rising_together_group attribute identifies the list of two or more input or output

pins that share logic and are rising during the same time period. This time period is defined

with the switching_interval attribute; see “switching_interval Simple Attribute” for

details.

Together, the rising_together_group attribute and switching_interval attribute

settings determine the level of power consumption.

Syntax

rising_together_group : "list of pins" ;

list of pins

The names of the input or output pins that share logic and are rising during

the same time period.

Example

cell (foo) {

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pin (A) {

internal_power () {

falling_together_group : "B C D" ;

rising_together_group : "E F G" ;

switching_interval : 10.0 ;

rise_power () {

...

}

fall_power () {

...

}

switching_interval Simple Attribute

The switching_interval attribute defines the time interval during which two or more

pins that share logic are falling, rising, or switching (either falling or rising) during the same

time period.

This attribute is set together with the falling_together_group,

rising_together_group, or switching_together_group attribute. Together with

one of these attributes, the switching_interval attribute defines a level of power

consumption.

For details about the attributes that are set together with the switching_interval

attribute, see “falling_together_group Simple Attribute ” , “rising_together_group Simple

Attribute ” , and “switching_together_group Simple Attribute ” .

Syntax

switching_interval : valuefloat ;

value

A floating-point number that represents the time interval during which two

or more pins that share logic are transitioning together.

Example

pin (Z) {

direction : output;

internal_power () {

switching_together_group : "A B";

/*if pins A, B, and Z switch*/ ;

switching_interval : 5.0;

/* switching within 5 time units */;

power () {

...

}

switching_together_group Simple Attribute

The switching_together_group attribute identifies a list of two or more input or output

pins that share logic, are either falling or rising during the same time period, and are not

affecting the power consumption.

The time period is defined with the switching_interval attribute. See

“switching_interval Simple Attribute” for details.

Syntax

switching_together_group : "list of pins" ;

list of pins

The names of the input or output pins that share logic, are either falling or

rising during the same time period, and are not affecting power

consumption.

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when Simple Attribute

The when attribute specifies the state-dependent condition that determines whether this

power table is accessed.

You can use the when attribute to define one-, two-, or three-dimensional tables in the

internal_power group. You can also use the when attribute in the power,

fall_power, and rise_power groups.

Note:

If you want to use the same Boolean expression for multiple when statements in an

internal_power group, you must specify a different power rail for each

internal_power group.

Syntax

when : "Boolean expression" ;

Boolean expression

The name or names of the input and output pins with corresponding

Boolean operators.

Table 3-3 lists the Boolean operators valid in a when statement.

Table 3-3 Valid Boolean Operators

Operator Description

' invert previous expression

! invert following expression

^ logical XOR

* logical AND

& logical AND

space logical AND

+ logical OR

| logical OR

1 signal tied to logic 1

0 signal tied to logic 0

The order of precedence of the operators is left to right, with inversion performed first, then

XOR, then AND, then OR.

Example

when : "A B" ;

fall_power Group

The fall_power group defines the power associated with a fall transition on a pin. You

specify a fall_power group in an internal_power group in a pin group, as shown

here.

cell (namestring) {

pin (namestring) {

internal_power () {

fall_power (template name) {

... fall power description ...

}

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Complex Attributes

index_1 ("float, ..., float") ; /* lookup table */

index_2 ("float, ..., float") ; /* lookup table */

index_3 ("float, ..., float" ; /* lookup table */

values ("float, ..., float") ; /* lookup table */

orders("integer, ..., integer") ; /* polynomial */

coefs("float, ..., float") ; /* polynomial */

float

Floating-point numbers that identify the amount of energy per fall transition

the cell consumes internally.

You convert the values attribute to power consumption by multiplying the

unit by the factor transition or per-unit time, as follows:

❍ nindex_1 floating-point numbers if the table is one-dimensional

❍ nindex_1 x nindex_2 floating-point numbers if the table is two-dimensional

❍ nindex_1 x nindex_2 x nindex_3 floating-point numbers if the table is three-

dimensional

nindex_1, nindex_2, and nindex_3 are the size of index_1,

index_2, and index_3 in this group or in the power_lut_template

group it inherits. Quotation marks (" ") enclose a group. Each group

represents a row in the table.

This power is accessed when the pin has a fall transition. If you have a

fall_power group, you must have a rise_power group.

Example 3-5 shows cells that contain internal power information in the pin

group.

Group Statement

domain (name) {}

name

References a domain group defined in the power_poly_template group

or the power_lut_template group.

power Group

Use the power group to define power when the rise power equals the fall power for a

particular pin. You specify a power group within an internal_power group in a pin

group at the cell level, as shown here:

Syntax

library (name) {

cell (name) {

pin (name) {

internal_power () {

power (template name) {

... power template description ...

}

Complex Attributes

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

index_3 ("float, ..., float") ;

values ("float, ..., float") ;

orders ("integer, ..., integer") ; /* polynomial */

coefs ("float, ..., float") ; /* polynomial */

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float

Floating-point numbers that identify the amount of energy per transition,

either rise or fall, the cell consumes internally.

You convert the values attribute to power consumption by multiplying the

unit by the factor transition or per-unit time, as follows:

❍ nindex_1 floating-point numbers if the table is one-dimensional

❍ nindex_1 x nindex_2 floating-point numbers if the table is two-dimensional

❍ nindex_1 x nindex_2 x nindex_3 floating-point numbers if the table is three-

dimensional

nindex_1, nindex_2, and nindex_3 are the size of index_1,

index_2, and index_3 in this group or in the power_lut_template

group it inherits. Quotation marks (" ") enclose a group. Each group

represents a row in the table.

This power is accessed when the pin has a rise transition or fall transition.

The values in the table specify the average power per transition.

Example 3-5 shows cells that contain power information in the

internal_power group in a pin group.

Group

domain (name) {}

name

References a domain group defined in the power_poly_template group

or the power_lut_template group.

rise_power Group

The rise_power group defines the power associated with a rise transition on a pin. You

specify a rise_power group in an internal_power group in a pin group, as shown

here:

Syntax

cell (name) {

pin (name) {

internal_power () {

rise_power (template name) {

... rise power description ...

}

Complex Attributes

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

index_3 ("float, ..., float");

values ("float, ..., float") ;

orders ("integer, ..., integer") ; /* polynomial */

coefs ("float, ..., float") ; /* polynomial */

float

Floating-point numbers that identify the amount of energy per rise transition

the cell consumes internally.

You convert the values attribute to power consumption by multiplying the

unit by the factor transition or per-unit time, as follows:

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❍ nindex_1 floating-point numbers if the table is one-dimensional

❍ nindex_1 x nindex_2 floating-point numbers if the table is two-dimensional

❍ nindex_1 x nindex_2 x nindex_3 floating-point numbers if the table is three-

dimensional

nindex_1, nindex_2, and nindex_3 are the size of index_1,

index_2, and index_3 in this group or in the power_lut_template

group it inherits. Quotation marks (" ") enclose a group. Each group

represents a row in the table.

This power is accessed when the pin has a rise transition.

Example 3-5 shows cells that contain internal power information in the pin

group.

Group

domain (name) {}

name

References a domain group defined in either the power_poly_template

group or the power_lut_template group.

Example 3-5 A Library With Internal Power

library(internal_power_example) {

...

power_lut_template(output_by_cap1_cap2_and_trans) {

variable_1 : total_output1_net_capacitance ;

variable_2 : equal_or_opposite_output_net_capacitance ;

variable_3 : input_transition_time ;

index_1 ("0.0, 5.0, 20.0") ;

index_2 ("0.0, 5.0, 20.0") ;

index_3 ("0.0, 1.0, 2.0") ;

}

power_lut_template(output_by_cap_and_trans) {

variable_1 : total_output_net_capacitance ;

variable_2 : input_transition_time ;

index_1 ("0.0, 5.0, 20.0") ;

index_2 ("0.0, 1.0, 2.0") ;

}

...

power_lut_template(input_by_trans) {

variable_1 : input_transition_time ;

index_1 ("0.0, 1.0, 2.0") ;

}

cell(AN2) {

pin(Z) {

direction : output;

internal_power() {

power (output_by_cap_and_trans) {

values ("2.2, 3.7, 4.3", "1.7, 2.1, 3.5", "1.0, 1.5, 2.8");

}

related_pin : "A B" ;

}

...

pin(A) {

direction : input ;

...

}

pin(B) {

direction : input ;

...

}

cell(FLOP1) {

pin(CP) {

direction : input ;

internal_power() {

power (input_by_trans) {

values ("1.5, 2.5, 4.7") ;

}

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}

pin(D) {

direction : input ;

...

}

pin(S) {

direction : input ;

...

}

pin(R) {

direction : input ;

...

}

pin(Q) {

direction : output ;

internal_power() {

power (output_by_cap1_cap2_and_trans) {

values ("2.2, 3.7, 4.3", "1.7, 2.1, 3.5", "1.0, 1.5, 2.8",\

"2.1, 3.6, 4.2", "1.6, 2.0, 3.4", "0.9, 1.5, 2.7",\

"2.0, 3.5, 4.1", "1.5, 1.9, 3.3", "0.8, 1.4, 2.6");

}

when : "S’ + R’" ;

equal_or_opposite_output : "QN" ;

related_pin : "CP" ;

}

internal_power() {

power (output_by_cap_and_trans) {

values ("1.8, 3.4, 4.0", "1.5, 1.9, 3.3", "0.8, 1.3, 2.5");

}

related_pin : "S R" ;

}

...

}

pin(QN) {

direction : output ;

internal_power() {

rise_power (output_by_cap_and_trans) {

values ("0.5, 0.9, 1.3", "0.3, 0.7, 1.1", "0.2, 0.5, 0.9");

}

fall_power (output_by_cap_and_trans) {

values ("0.1, 0.7, 0.9", "-0.1, 0.2, 0.4", "-0.2, 0.2, 0.3");

}

related_pin : "S R" ;

}

...

}

...

}

3.2.9 max_cap Group

The max_cap group defines the frequency-based maximum capacitance information for the

output and inout pins.

Syntax

library (name) {

cell (name) {

pin (name) {

max_cap (template name) {

... capacitance description ...

}

template_name

A value representing the name of a maxcap_lut_template group.

Example

max_cap ( ) {

...

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}

3.2.10 max_trans Group

Use the max_trans group to describe the maximum transition information for output and

inout pins.

Syntax

library (name) {

cell (name) {

pin (name) {

max_trans ( template_nameid ) {

... transition description ...

}

template_name

A value representing the name of a maxtrans_lut_template group.

Complex Attributes

variable_1_range

variable_2_range

variable_n_range

orders

coefs

Example

max_trans ( ) {

...

}

3.2.11 min_pulse_width Group

In a pin, bus, or bundle group, the min_pulse_width group models the enabling

conditional minimum pulse width check. In the case of a pin, the timing check is performed

on the pin itself, so the related pin must be the same.

Syntax

pin() {

...

min_pulse_width() {

constraint_high : value ;

constraint_low : value ;

when : "Boolean expression" ;

/* enabling condition */

sdf_cond : "Boolean expression" ;

/* in SDF syntax */

}

Example

pin(A) {

. . .

min_pulse_width() {

constraint_high : 3.0 ;

constraint_low : 3.5 ;

when : "SE" ;

sdf_cond : "SE == 1’B1" ;

}

Simple Attributes

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constraint_high

constraint_low

when

sdf_cond

constraint_high Simple Attribute

The constraint_high attribute defines the minimum length of time the pin must remain

at logic 1. You define a value for either constraint_high, constraint_low, or both

in the min_pulse_width group.

Syntax

constraint_high : valuefloat ;

value

A nonnegative number.

Example

constraint_high : 3.0 ; /* min_pulse_width_high */

when Simple Attribute

The when attribute defines the enabling condition for the check in Synopsys logic

expression format.

Syntax

when : "Boolean expression" ;

Boolean expression

A logic expression.

For a list of Boolean operators, see Table 3-3.

Example

when : "SE" ;

constraint_low Simple Attribute

The constraint_low attribute defines the minimum length of time the pin must remain at

logic 0. You define a value for either constraint_low, constraint_high, or both in

the min_pulse_width group.

Syntax

constraint_low : valuefloat ;

value

A nonnegative number.

Example

constraint_low : 3.5 ; /* min_pulse_width_low */

sdf_cond Simple Attribute

The sdf_cond attribute defines the enabling condition for the check in Open Verilog

International (OVI) Standard Delay Format (SDF) 2.1 syntax.

Syntax

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sdf_cond : "Boolean expression" ;

Boolean expression

An SDF condition expression.

Example

sdf_cond : "SE == 1’B1" ;

3.2.12 minimum_period Group

In a pin, bus, or bundle group, the minimum_period group models the enabling

conditional minimum period check. In the case of a pin, the check is performed on the pin

itself, so the related pin must be the same.

If the pin group contains a minimum_period group and a min_period attribute, the

min_period attribute is ignored.

Syntax

minimum_period() {

constraint : value ;

when : "Boolean expression" ;

sdf_cond : "Boolean expression" ;

}

Simple Attributes

constraint

when

sdf_cond

constraint Simple Attribute

This required attribute defines the minimum clock period for the pin.

Syntax

constraint : valuefloat ;

value

A nonnegative number.

Example

constraint : 9.5 ;

when Simple Attribute

This required attribute defines the enabling condition for the check in Synopsys logic

expression format.

Syntax

when : "Boolean expression" ;

Boolean expression

A logic expression.

For a list of Boolean operators, see Table 3-3.

Example

when : "SE" ;

sdf_cond Simple Attribute

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This required attribute defines the enabling condition for the check in OVI SDF 2.1 syntax.

Syntax

sdf_cond : "Boolean expression" ;

Boolean expression

An SDF condition expression.

Example

sdf_cond : "SE == 1’b1" ;

3.2.13 pin_capacitance Group

In a pin group, the pin_capacitance group supports polynomial equation modeling to

represent capacitance, rise_capacitance, fall_capacitance,

rise_capacitance_range, and fall_capacitance_range.

The existing single value capacitance, rise_capacitance, fall_capacitance,

rise_capacitance_range and fall_capacitance_range attributes and the new

pin_capacitance group can co-exist on one pin. The syntax for the pin_capacitance

group is the same used for the delay model, except that the variables used in the format

are temperature and voltage (including power rails).

The pin_capacitance group supports only the scalable polynomial delay model.

Note:

The capacitance group is required In the pin_capacitance group.

Group Statements

capacitance

rise_capacitance

fall_capacitance

fall_capacitance_range

rise_capacitance _range

Syntax

pin_capacitance() {...pin_capacitance description ...

}

capacitance Group

Use the capacitance group to define the load of an input, output, inout, or internal pin.

This group is required in the pin_capacitance group.

Syntax

capacitance() {...capacitance description ...}

Example

capacitance(cap) {

orders ("1 , 1");

coefs ("1, 2, 3, 4");

}

fall_capacitance Group

Use the fall_capacitance group to define the load of an input, output, inout, or internal

pin when its signal is falling. You must set a value for both the rise_capacitance and

fall_capacitance groups.

The value you set for a fall_capacitance group overrides the value you set for a

fall_capacitance simple attribute.

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Syntax

fall_capacitance() {...capacitance description ...}

Example

fall_capacitance(fall_cap) {

orders ("1 , 1");

coefs ("1, 2, 3, 4");

}

rise_capacitance Group

Use the rise_capacitance group to define the load of an input, output, inout, or internal

pin when its signal is rising. For more information, see “fall_capacitance Group” .

fall_capacitance_range Group

This group describes the range for temperature and voltage (including voltage rails) during

fall transitions. Only one fall_capacitance_range or rise_capacitance_range

group is allowed inside the pin_capacitance group.The rise and fall capacitance range

groups are optional.

Syntax

fall_capacitance_range() {... values description ...}

Groups

lower upper

lower Group

For pin_capacitance, use this group to specify a range of minimum and maximum float

values or polynomials as a function of temperature and voltage (including power rails).

You must define both the lower and upper groups in a rise_capacitance_range or

fall_capacitance_range group.

Syntax

lower (poly_template_name id) {... values description ...}

Example

lower(cap) {

...

orders ("1 , 1");

coefs ("1, 2, 3, 4");

}

Complex Attributes

variable_1_range

variable_2_range

variable_n_range

orders

coefs

variable_ n _range Complex Attribute

Use the variable_ n _range attribute to specify the range of the value for the n th

variable in the variables attribute.

Syntax

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variable_n_range(min_1float, max_2float) ;

min , max

Floating-point number pairs that specify the value range.

Example

fall_capacitance_range () {

lower(cap) {

...

orders ("1 , 1");

coefs ("1, 2, 3, 4");

}

upper(cap) {

...

orders ("1 , 1");

coefs ("1, 2, 3, 4");

}

coefs Complex Attribute

Use the coefs attribute to specify a list of the coefficients you use in a polynomial. For

more information, see “coefs Complex Attribute” .

orders Complex Attribute

Use the orders attribute to specify the order for the variables for the polynomial. For more

information, see “orders Complex Attribute” .

upper Group

For pin_capacitance, use this group to specify a range of minimum and maximum float

values or polynomials as a function of temperature and voltage (including power rails). For

more information, see “lower Group” .

rise_capacitance_range Group

This group describes the range of pin capacitance as a function of temperature and voltage

(including voltage rails) during rise transitions for the signal. For more information, see

“fall_capacitance_range Group” .

Example

Example 3-6 shows a sample library with extended rise_capacitance_range and

fall_capacitance_range syntax.

Example 3-6 Sample Library With pin_capacitance Group Values

library(new_lib) {

. . .

poly_template (PPT) {

variables ("temperature", "voltage");

variable_1_range (-40.0, 100.0);

variable_2_range (0.5, 3.5);

domain (D1) {

calc_mode : best ;

}

domain (D2) {

calc_mode : worst ;

}

. . .

cell(AN2){

pin(Y) {

...

pin_capacitance() {

/* default poly capcaitance */

capacitance(PPT) {

orders ("1, 1");

coefs ("0.11, 0.12, 0.13, 0.14");

domain (D1) {

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orders ("1, 1");

coefs ("0.21, 0.22, 0.23, 0.24");

}

domain (D2) {

orders ("1, 1");

coefs ("0.31, 0.32, 0.33, 0.34");

}

rise_capacitance(PPT) {

orders ("1, 1");

coefs ("0.11, 0.12, 0.13, 0.14");

domain (D1) {

orders ("1, 1");

coefs ("0.21, 0.22, 0.23, 0.24");

}

domain (D2) {

orders ("1, 1");

coefs ("0.31, 0.32, 0.33, 0.34");

}

fall_capacitance(PPT) {

orders ("1, 1");

coefs ("0.11, 0.12, 0.13, 0.14");

domain (D1) {

orders ("1, 1");

coefs ("0.21, 0.22, 0.23, 0.24");

}

domain (D2) {

orders ("1, 1");

coefs ("0.31, 0.32, 0.33, 0.34");

}

rise_capacitance_range() {

lower(PPT) {

orders ("1, 1");

coefs ("0.01, 0.02, 0.03, 0.04");

domain (D1) {

orders ("1, 1");

coefs ("0.11, 0.12, 0.13, 0.14");

}

domain (D2) {

orders ("1, 1");

coefs ("0.21, 0.22, 0.23, 0.24");

}

upper(PPT) {

orders ("1, 1");

coefs ("0.21, 0.22, 0.23, 0.24");

domain (D1) {

orders ("1, 1");

coefs ("0.31, 0.32, 0.33, 0.34");

}

domain (D2) {

orders ("1, 1");

coefs ("0.41, 0.42, 0.43, 0.44");

}

fall_capacitance_range() {

lower(PPT) {

orders ("1, 1");

coefs ("0.01, 0.02, 0.03, 0.04");

domain (D1) {

orders ("1, 1");

coefs ("0.11, 0.12, 0.13, 0.14");

}

domain (D2) {

orders ("1, 1");

coefs ("0.21, 0.22, 0.23, 0.24");

}

upper(PPT) {

orders ("1, 1");

coefs ("0.21, 0.22, 0.23, 0.24");

domain (D1) {

orders ("1, 1");

coefs ("0.31, 0.32, 0.33, 0.34");

}

domain (D2) {

orders ("1, 1");

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coefs ("0.41, 0.42, 0.43, 0.44");

}

3.2.14 receiver_capacitance Group

Use the receiver_capacitance group to specify capacitance values for composite

current source (CCS) receiver modeling at the pin level.

Syntax

library (namestring) {

cell (namestring) {

pin (namestring) {

receiver_capacitance (){

... description ...

}

Groups

receiver_capacitance1_fall

receiver_capacitance1_rise

receiver_capacitance2_fall

receiver_capacitance2_rise

receiver_capacitance1_fall Group

You can define the receiver_capacitance1_fall group at the pin level and the timing level.

Define the receiver_capacitance1_fall group at the pin level to reference a

composite current source (CCS) template. For information about using the group at the

timing level, see “receiver_capacitance1_fall Group” .

Syntax

receiver_capacitance1_fall (lu_template_nameid) {

lu_template_name

The name of a template.

Complex Attribute

values

Example

receiver_capacitance () {

receiver_capacitance1_rise (LTT1) {

values (0.0, 0.0, 0.0, 0.0) ;

}

receiver_capacitance1_fall (LTT1) {

...

}

...

}

receiver_capacitance1_rise Group

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For information about using the receiver_capacitance1_rise group, see the

description of the .”

receiver_capacitance2_fall Group

For information about using the receiver_capacitance2_fall group, see the

description of .”

receiver_capacitance2_rise Group

For information about using the receiver_capacitance2_rise group, see the

description of the .”

3.2.15 timing Group in a pin Group

A timing group is defined within a pin group, as shown here. Note that the syntax

presents the attributes in alphabetical order by type of attribute.

Entering the names in the timing group attribute to identify timing arcs is optional.

Syntax

library (namestring) {

cell (namestring) {

pin (namestring) {

timing (namestring){

... timing description ...

}

Simple Attributes

clock_gating_flag : true|false ;

default_timing : true|false ;

fall_resistance : float ;

fpga_arc_condition : "Boolean expression" ;

fpga_domain_style : name ;

interdependence_id : integer ;

intrinsic_fall : float ;

intrinsic_rise : float ;

related_bus_equivalent : " name1 [name2 name3 ... ] " ;

related_bus_pins : " name1 [name2 name3 ... ] " ;

related_output_pin : name ;

related_pin : " name1 [name2 name3 ... ] " ;

rise_resistance : float ;

sdf_cond : "SDF expression" ;

sdf_cond_end : "SDF expression" ;

sdf_cond_start : "SDF expression" ;

sdf_edges : SDF edge type ;

slope_fall : float ;

slope_rise : float ;

steady_state_resistance_above_high : float ;

steady_state_resistance_below_low : float ;

steady_state_resistance_high : float ;

steady_state_resistance_low : float ;

tied_off: Boolean ;

timing_sense : positive_unate| negative_unate| non_unate;

timing_type : combinational | combinational_rise |

combinational_fall | three_state_disable |

three_state_disable_rise | three_state_disable_fall |

three_state_enable | three_state_enable_rise |

three_state_enable_fall |rising_edge | falling_edge |

preset | clear | hold_rising | hold_falling |

setup_rising | setup_falling | recovery_rising |

recovery_falling | skew_rising | skew_falling |

removal_rising | removal_falling | min_pulse_width |

minimum_period | max_clock_tree_path |

min_clock_tree_path |non_seq_setup_rising |

non_seq_setup_falling | non_seq_hold_rising |

non_seq_hold_falling | nochange_high_high |

nochange_high_low | nochange_low_high |

nochange_low_low ;

when : "Boolean expression" ;

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when_end : "Boolean expression" ;

when_start : "Boolean expression" ;

Complex Attributes

fall_delay_intercept (integer, float) ; /* piecewise model only */

fall_pin_resistance (integer, float) ; /* piecewise model only */

mode

rise_delay_intercept (integer, float) ; /* piecewise model only */

rise_pin_resistance (integer, float) ; /* piecewise model only */

Group Statements

cell_degradation () { }

cell_fall () { }

cell_rise () { }

fall_constraint () { }

fall_propagation () { }

fall_transition () { }

noise_immunity_above_high () { }

noise_immunity_below_low () { }

noise_immunity_high () { }

noise_immunity_low () { }

output_current_fall () { }

output_current_rise () { }

propogated_noise_height_above_high () { }

propogated_noise_height_below_low () { }

propogated_noise_height_high () { }

propogated_noise_height_low () { }

propogated_noise_peak_time_ratio_above_high () { }

propogated_noise_peak_time_ratio__below_low () { }

propogated_noise_peak_time_ratio_high () { }

propogated_noise_peak_time_ratio_low () { }

propogated_noise_width_above_high () { }

propogated_noise_width_below_low () { }

propogated_noise_width_high () { }

propogated_noise_width_low () { }

receiver_capacitance1_fall () { }

receiver_capacitance1_rise () { }

receiver_capacitance2_fall () { }

receiver_capacitance2_rise () { }

retaining_fall () { }

retaining_rise () { }

retain_fall_slew () { }

retain_rise_slew () { }

rise_constraint () { }

rise_propagation () { }

rise_transition () { }

steady_state_current_high () { }

steady_state_current_low () { }

steady_state_current_tristate () { }

clock_gating_flag Simple Attribute

Use this attribute to indicate that a constraint arc is for a clock gating relation between the

data and clock pin, instead of a constraint found in standard sequential devices, such as

registers and latches.

Syntax

clock_gating_flag : Boolean ;

Boolean

Valid values are true and false. The value true is applicable only when the

value of the timing_type attribute is setup, hold, or nochange. When not

defined for a timing arc, the value false is assumed, indicating the timing

arc is part of a standard sequential device.

Example

clock_gating_flag : true ;

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default_timing Simple Attribute

The default_timing attribute allows you to specify one timing arc as the default in the

case of multiple timing arcs with when statements.

Syntax

default_timing : Boolean expression ;

Example

default_timing : true ;

fall_resistance Simple Attribute

The fall_resistance attribute represents the load-dependent output resistance, or

drive capability, for a logic 1-to-0 transition.

Note:

You cannot specify a resistance unit in the library. Instead, the resistance unit is derived

from the ratio of the time_unit value to the capacitive_load_unit value.

Syntax

fall_resistance : valuefloat ;

value

A positive floating-point number in terms of delay time per load unit.

Example

fall_resistance : 0.18 ;

fpga_arc_condition Simple Attribute

The fpga_arc_condition attribute specifies a Boolean condition that enables a timing

arc.

Syntax

fpga_arc_condition : conditionBoolean ) ;

condition

Specifies a Boolean condition. Valid values are true and false.

Example

fpga_arc_condition : ;

fpga_domain_style Simple Attribute

Use this attribute to reference a calc_mode value in a domain group in a polynomial

table.

Syntax

fpga_domain_style : "nameid" ;

name

The calc_mode value.

Example

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fpga_domain_style : "speed";

interdependence_id Simple Attribute

Use pairs of interdependence_id attributes to identify interdependent pairs of setup

and hold constraint tables. Interdependence data is supported in conditional constraint

checking, the interdependence_id attribute increases independently for each condition.

Interdependence data can be specified in pin, bus, and bundle groups.

Syntax

interdependence_id : "nameenum" ;

name

Valid values are 1, 2, 3, and so on.

Examples

timing()

related_pin : CLK ;

timing_type: setup_rising ;

interdependence_id : 1 ;

...

timing()

related_pin : CLK ;

timing_type: setup_rising ;

interdependence_id : 2 ;

...

pin (D_IN) {

…

/* original non-conditional setup/hold constraints */

setup/hold constraints

/* new interdependence data for non-conditional constraint

checking */

setup/hold, interdependent_id = 1

setup/hold, interdependent_id = 2

setup/hold, interdependent_id = 3

/* original setup/hold constraints for conditional

<condition_a> */

setup/hold when <condition_a>

/* new interdependence data for <condition_a> constraint

checking */

setup/hold when <condition_a>, interdependent_id = 1

setup/hold when <condition_a>, interdependent_id = 2

setup/hold when <condition_a>, interdependent_id = 3

/* original setup/hold constraints for conditional

<condition_b> */

setup/hold when <condition_b>

/* new interdependence data for <condition_b> constraint

checking */

setup/hold when <condition_b>, interdependent_id = 1

setup/hold when <condition_b>, interdependent_id = 2

setup/hold when <condition_b>, interdependent_id = 3

}

Guidelines:

● To prevent potential backward-compatibility issues, interdependence data

cannot be the first timing arc in the pin group.

● The interdependence_id attribute only supports the following timing types:

setup_rising, setup_falling, hold_rising, and hold_falling . If you

set this attribute on other timing types, an error is reported.

● You must specify setup and hold interdependence data in pairs; otherwise an

error is reported. If you define one setup_rising timing arc with

interdependence_id: 1; on a pin, you must also define a hold_rising

timing arc with interdependence_id: 1; for that pin. The

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interdependence_id could be a random integer, but it must be found in a pair of

timing arcs. These timing types are considered as pairs: setup_rising with

hold_rising and setup_falling with hold_falling.

● For each set of conditional constraints (non-conditional categorized as a special

condition), a timing arc with a specific interdependence_id should be unique

in a pin group.

● For each set of conditional constraints, the interdependence_id must start

from 1, and if there is multiple interdependence data defined, the values for the

interdependence_id should be in consecutive order. That is, 1, 2, 3 is allowed,

but 1, 2, 4 is not.

intrinsic_fall Simple Attribute

On an output pin, intrinsic_fall defines the 1-to-Z propagation time for a three-state-

disable timing type and the Z-to-0 propagation time for a three-state-enable timing type.

On an input pin, intrinsic_fall defines a setup, hold, or recovery timing requirement

for a logic 1-to-0 transition.

With intrinsic_rise, intrinsic_fall defines timing checks (rising and falling

transitions).

Syntax

intrinsic_fall : valuefloat ;

value

A floating-point number that represents a timing requirement.

Example

intrinsic_fall : 0.75 ;

intrinsic_rise Simple Attribute

On an output pin, intrinsic_rise defines the 0-to-Z propagation time for a three-state-

disable timing type and a Z-to-1 propagation time for a three-state-enable timing type.

On an input pin, intrinsic_rise defines a setup, hold, or recovery timing requirement

for a logic 0-to-1 transition.

With intrinsic_fall, intrinsic_rise defines timing checks (rising and falling

transitions).

Syntax

intrinsic_rise : valuefloat ;

value

A floating-point number that represents a timing requirement.

Example

intrinsic_rise : 0.17 ;

related_bus_equivalent Simple Attribute

The related_bus_equivalent attribute generates a single timing arc for all paths from

points in a group through an internal pin (I) to given endpoints.

Syntax

related_bus_equivalent : " name1 [name2 name3 ... ] " ;

Example

related_bus_equivalent : a ;

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Example 3-7 shows an example using equivalent bus pins.

Example 3-7 Equivalent Bus Pins

cell(acell) {

...

bus(y) {

bus_type : bus4;

direction : output;

timing() {

related_bus_equivalent : a;

...

}

bus(a) {

bus_type : bus4;

direction : input;

...

}

related_bus_pins Simple Attribute

The related_bus_pins attribute defines the pin or pins that are the startpoint of the

timing arc. The primary use of related_bus_pins is for module generators.

Note:

When a related_bus_pins attribute is within a timing group, the timing group must

be within a bus or bundle group.

Syntax

related_bus_pins : " name1 [name2 name3 ... ] " ;

Example

related_bus_pins : "A" ;

related_output_pin Simple Attribute

The related_output_pin attribute specifies the output or inout pin used to describe a

load-dependent constraint. This is an attribute in the timing group of the output or inout

pin.The pin defined must be a pin in the same cell, and its direction must be either output or

inout.

Syntax

related_output_pin : name ;

Example

related_output_pin : Z ;

related_pin Simple Attribute

The related_pin attribute defines the pin or pins representing the beginning point of the

timing arc. It is required in all timing groups.

Syntax

related_pin : "name1 [name2 name3 ... ]" ;

In a cell with input pin A and output pin B, define A and its relationship to B in the

related_pin attribute statement in the timing group that describes pin B.

Example

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pin (B){

direction : output ;

function : "A’";

timing () {

related_pin : "A" ;

... timing information ...

}

The related_pin attribute statement can also serve as a shortcut for two identical timing

arcs for a cell. For example, in a 2-input NAND gate with identical delays from both input

pins to the output pin, it is necessary to define only one timing arc with two related pins.

Example

pin (Z) {

direction : output;

function : "(A * B)’" ;

timing () {

related_pin : "A B" ;

... timing information ...

}

When a bus name appears in a related_pin attribute, the bus members or range of

members is distributed across all members of the parent bus. The width of the bus or the

range must be the same as the width of the parent bus.

Pin names used in a related_pin statement can start with a nonalphabetic character.

Example

related_pin : "A 1B 2C" ;

Note:

It is not necessary to use the escape character, \ (backslash), with nonalphabetic

characters.

rise_resistance Simple Attribute

The rise_resistance attribute represents the load-dependent output resistance, or

drive capability, for a logic 0-to-1 transition.

Note:

You cannot specify a resistance unit in the library. Instead, the resistance unit is derived

from the ratio of the time_unit value to the capacitive_load_unit value.

Syntax

rise_resistance : valuefloat ;

value

A positive floating-point number in terms of delay time per load unit.

Example

rise_resistance : 0.15 ;

sdf_cond Simple Attribute

The sdf_cond attribute is defined in the state-dependent timing group to support SDF

file generation and condition matching during back-annotation.

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Syntax

sdf_cond : "SDF expression" ;

SDF expression

A string that represents a Boolean description of the state dependency of

the delay. Use a Boolean description that conforms to the valid syntax

defined in the OVI SDF, which is different from the Synopsys Boolean

expression syntax. For a complete description of the valid syntax for these

expressions, refer to the OVI specification for SDF, v1.0.

Example

sdf_cond : "b == 1’b1" ;

sdf_cond_end Simple Attribute

The sdf_cond_end attribute defines a timing-check condition specific to the end event in

VHDL models. The expression must conform to OVI SDF 2.1 timing-check condition syntax.

Syntax

sdf_cond_end : "SDF expression" ;

SDF expression

An SDF expression containing names of input, output, inout, and internal

pins.

Example

sdf_cond_end : "SIG_0 == 1’b1" ;

sdf_cond_start Simple Attribute

The sdf_cond_start attribute defines a timing-check condition specific to the start event

in full-timing gate-level simulation (FTGS) models. The expression must conform to OVI

SDF 2.1 timing-check condition syntax.

Syntax

sdf_cond_start : "SDF expression" ;

SDF expression

An SDF expression containing names of input, output, inout, and internal

pins.

Example

sdf_cond_start : "SIG_2 == 1’b1" ;

sdf_edges Simple Attribute

The sdf_edges attribute defines the edge specification on both the start pin and the end

pin. The default is noedge.

Syntax

sdf_edges : sdf_edge_type;

sdf_edge_type

One of these four edge types: noedge, start_edge, end_edge, or

both_edges. The default is noedge.

Example

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sdf_edges : both_edges;

sdf_edges : start_edge ; /* edge specification on starting pin */

sdf_edges : end_edge ; /* edge specification on end pin */

sensitization_master Simple Attribute

The sensitization_master attribute defines the sensitization group specific to the

current timing group to generate stimulus for characterization. The attribute is optional

when the sensitization master used for the timing arc is the same as that defined in the

current cell. It is required when they are different. Any sensitization group name

predefined in the current library is a valid attribute value.

Syntax

sensitization_master : sensitization_group_name;

sensitization_group_name

A string identifying the sensitization group name predefined in the

current library.

Example

sensitization_master : sensi_2in_1out;

slope_fall Simple Attribute

The slope_fall attribute represents the incremental delay to add to the slope of the input

waveform for a logic 1-to-0 transition.

Syntax

slope_fall : valuefloat ;

value

A positive floating-point number multiplied by the transition delay resulting

in slope delay.

Example

slope_fall : 0.8 ;

slope_rise Simple Attribute

The slope_rise attribute represents the incremental delay to add to the slope of the input

waveform for a logic 0-to-1 transition.

Syntax

slope_rise : valuefloat ;

value

A positive floating-point number multiplied by the transition delay resulting

in slope delay.

Example

slope_rise : 1.0 ;

steady_state_resistance_above_high Simple Attribute

The steady_state_resistance_above_high attribute specifies a steady-state

resistance value for a region of a current-voltage (I-V) curve when the output is high and

the noise is over the high voltage rail.

Syntax

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steady_state_resistance_above_high : valuefloat ;

value

A positive floating-point number that represents the resistance. The

resistance unit is a function of the unit of time divided by the library unit of

capacitance.

Example

steady_state_resistance_above_high : 200 ;

steady_state_resistance_below_low Simple Attribute

The steady_state_resistance_below_low attribute specifies a steady-state

resistance value for a region of a current-voltage (I-V) curve when the output is low and the

noise is below the low voltage rail.

Syntax

steady_state_resistance_below_low : valuefloat ;

value

A positive floating-point number that represents the resistance. The

resistance unit is a function of the unit of time divided by the library unit of

capacitance.

Example

steady_state_resistance_below_low : 100 ;

steady_state_resistance_high Simple Attribute

The steady_state_resistance_high attribute specifies a steady-state resistance

value for a region of a current-voltage (I-V) curve when the output is high and the noise is

below the high voltage rail.

Syntax

steady_state_resistance_high : valuefloat ;

value

A positive floating-point number that represents the resistance. The

resistance unit is a function of the unit of time divided by the library unit of

capacitance.

Example

steady_state_resistance_high : 1500 ;

steady_state_resistance_low Simple Attribute

The steady_state_resistance_low attribute specifies a steady-state resistance value

for a region of a current-voltage (I-V) curve when the output is low and the noise is over the

low voltage rail.

Syntax

steady_state_resistance_low : valuefloat ;

value

A positive floating-point number that represents the resistance. The

resistance unit is a function of the unit of time divided by the library unit of

capacitance.

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Example

steady_state_resistance_low : 1100 ;

tied_off Simple Attribute

Used for noise modeling, the tied_off attribute allows you to specify the I-V

characteristics and steady-state resistance values on tied-off cells.

Syntax

tied_off : Boolean ;

Boolean

Valid values are true and false.

Example

tied_off : true ;

timing_sense Simple Attribute

The timing_sense attribute describes the way an input pin logically affects an output pin.

Syntax

timing_sense : positive_unate | negative_unate

| non_unate ;

positive_unate

Combines incoming rise delays with local rise delays and compares

incoming fall delays with local fall delays.

negative_unate

Combines incoming rise delays with local fall delays and compares

incoming fall delays with local rise delays.

non_unate

Combines local delays with the worst-case incoming delay value. The non-

unate timing sense represents a function whose output value change

cannot be determined from the direction of the change in the input value.

Timing sense is derived from the logic function of a pin. For example, the value derived for

an AND gate is positive_unate, the value for a NAND gate is negative_unate, and the value

for an XOR gate is non_unate.

A function is said to be unate if a rising (falling) change on a positive (negative) unate input

variable causes the output function variable to rise (fall) or not change. For a non-unate

variable, further state information is required to determine the effects of a particular state

transition.

You can specify half-unate sequential timing arcs if the timing_type value is either

rising_edge or falling_edge and the timing_sense value is either positive_unate or

negative_unate.

● In the case of rising_edge and positive_unate values, only the cell_rise and

rise_transition information is required.

● In the case of rising_edge and negative_unate values, only the cell_fall and

fall_transition information is required.

● In the case of falling_edge and positive_unate values, only the cell_rise and

rise_transition information is required.

● In the case of falling_edge and negative_unate values, only the cell_fall and

fall_transition information is required.

Do not define the timing_sense value of a pin, except when you need to override the

derived value or when you are characterizing a noncombinational gate such as a three-

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state component. For example, you might want to define the timing sense manually when

you model multiple paths between an input pin and an output pin, such as in an XOR gate.

It is possible that one path is positive unate while another is negative unate. In this case,

the first timing arc is given a positive_unate designation and the second is given a

negative_unate designation.

Timing arcs with a timing type of clear or preset require a timing_sense attribute.

If related_pin is an output pin, you must define a timing_sense attribute for that pin.

timing_type Simple Attribute

The timing_type attribute distinguishes between combinational and sequential cells by

defining the type of timing arc. If this attribute is not assigned, the cell is considered

combinational.

Syntax

timing_type : combinational | combinational_rise

|

combinational_fall | three_state_disable |

three_state_disable_rise | three_state_disable_fall |

three_state_enable | three_state_enable_rise |

three_state_enable_fall | rising_edge | falling_edge |

preset | clear | hold_rising | hold_falling |

setup_rising | setup_falling | recovery_rising |

recovery_falling | skew_rising | skew_falling |

removal_rising | removal_falling | min_pulse_width |

minimum_period | max_clock_tree_path |

min_clock_tree_path |non_seq_setup_rising |

non_seq_setup_falling | non_seq_hold_rising |

non_seq_hold_falling | nochange_high_high |

nochange_high_low | nochange_low_high |

nochange_low_low ;

Combinational Timing Arcs

The timing type and timing sense define the signal propagation pattern. The default timing

type is combinational.

Table 3-4 Combinational Timing Arcs

Timing type Timing sense

Positive_Unate Negative_Unate Non_Unate

combinational R->R,F->F R->F,F->R {R,F}->{R,F}

combinational_rise R->R F->R {R,F}->R

combinational_fall F->F R->F {R,F}->F

three_state_disable R->{0Z,1Z} F->{0Z,1Z} {R,F}->{0Z,1Z}

three_state_enable R->{Z0,Z1} F->{Z0,Z1} {R,F}->{Z0,Z1}

three_state_disable_rise

R->0Z F->0Z {R,F}->0Z

three_state_disable_fall R->1Z F->1Z {R,F}->1Z

three_state_enable_rise R->Z1 F->Z1 {R,F}->Z1

three_state_enable_fall R->Z0 F->Z0 {R,F}->Z0

Sequential Timing Arcs

rising_edge

Identifies a timing arc whose output pin is sensitive to a rising signal at the

input pin.

falling_edge

Identifies a timing arc whose output pin is sensitive to a falling signal at the

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input pin.

preset

Preset arcs affect only the rise arrival time of the arc’s endpoint pin. A

preset arc implies that you are asserting a logic 1 on the output pin when

the designated related_pin is asserted.

clear

Clear arcs affect only the fall arrival time of the arc’s endpoint pin. A clear

arc implies that you are asserting a logic 0 on the output pin when the

designated related_pin is asserted.

hold_rising

Designates the rising edge of the related pin for the hold check.

hold_falling

Designates the falling edge of the related pin for the hold check.

setup_rising

Designates the rising edge of the related pin for the setup check on

clocked elements.

setup_falling

Designates the falling edge of the related pin for the setup check on

clocked elements.

recovery_rising

Uses the rising edge of the related pin for the recovery time check. The

clock is rising-edge-triggered.

recovery_falling

Uses the falling edge of the related pin for the recovery time check. The

clock is falling-edge-triggered.

skew_rising

The timing constraint interval is measured from the rising edge of the

reference pin (specified in related_pin) to a transition edge of the

parent pin of the timing group. The intrinsic_rise value is the

maximum skew time between the reference pin rising and the parent pin

rising. The intrinsic_fall value is the maximum skew time between

the reference pin rising and the parent pin falling.

skew_falling

The timing constraint interval is measured from the falling edge of the

reference pin (specified in related_pin) to a transition edge of the

parent pin of the timing group. The intrinsic_rise value is the

maximum skew time between the reference pin falling and the parent pin

rising. The intrinsic_fall value is the maximum skew time between

the reference pin falling and the parent pin falling.

removal_rising

Used when the cell is a low-enable latch or a rising-edge-triggered flip-flop.

For active-low asynchronous control signals, define the removal time with

the intrinsic_rise attribute. For active-high asynchronous control

signals, define the removal time with the intrinsic_fall attribute.

removal_falling

Used when the cell is a high-enable latch or a falling-edge-triggered flip-

flop. For active-low asynchronous control signals, define the removal time

with the intrinsic_rise attribute. For active-high asynchronous control

signals, define the removal time with the intrinsic_fall attribute.

minimum_pulse_width

This value, together with the minimum_period value, lets you specify the

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minimum pulse width for a clock pin. The timing check is performed on the

pin itself, so the related pin should be the same. As with other timing

checks, you can include rise and fall constraints.

minimum_period

This value, together with the minimum_pulse_width value, lets you

specify the minimum pulse width for a clock pin. The timing check is

performed on the pin itself, so the related pin should be the same. As with

other timing checks, you can include rise and fall constraints.

max_clock_tree_path

Used in timing groups under a clock pin. Defines the maximum clock tree

path constraint.

min_clock_tree_path

Used in timing groups under a clock pin. Defines the minimum clock tree

path constraint.

Example

Example 3-8 shows a sample library with the timing_type attribute and

minimum_pulse_width and minimum_period values.

Example 3-8 Sample Library with timing_type Statements

library(ASIC) {

...

delay_model : table_lookup;

....

lu_table_template(pulse_width_template) {

variable_1 : related_pin_transition;

index_1 ("1.0, 2.0, 3.0");

}

cell(flop) {

...

pin(CK) {

direction : input;

capacitance : 0.00707171;

timing() {

timing_type : "min_pulse_width";

related_pin : "CK";

...

rise_constraint("pulse_width_template") {

index_1("0.000000, 1.000000, 2.00000");

values ("6.000000, 6.250000, 7.2500000" );

}

fall_constraint("pulse_width_template") {

index_1("0.000000, 1.000000, 2.00000");

values ("6.000000, 6.250000, 7.2500000" );

}

timing() {

timing_type : "minimum_period";

related_pin : "CK";

rise_constraint("pulse_width_template") {

index_1(" .000000, 1.000000, 2.00000");

values ("6.000000, 6.250000, 7.2500000" );

}

fall_constraint("pulse_width_template") {

index_1("0.000000, 1.000000, 2.00000");

values ("6.000000, 6.250000, 7.2500000" );

}

....

} /* end cell */

} /* end library */

Nonsequential Timing Arcs

In some nonsequential cells, the setup and hold timing constraints are specified on the data

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pin with a nonclock pin as the related pin. It requires the signal of a pin to be stable for a

specified period of time before and after another pin of the same cell range state so that the

cell can function as expected.

non_seq_setup_rising

Defines (with non_seq_setup_falling) the timing arcs used for setup

checks between pins with nonsequential behavior. The related pin in a

timing arc is used for the timing check.

non_seq_setup_falling

Defines (with non_seq_setup_rising) the timing arcs used for setup

checks between pins with nonsequential behavior. The related pin in a

timing arc is used for the timing check. .

non_seq_hold_rising

Defines (with non_seq_hold_falling) the timing arcs used for hold

checks between pins with nonsequential behavior. The related pin in a

timing arc is used for the timing check.

non_seq_hold_falling

Defines (with non_seq_hold_rising) the timing arcs used for hold

checks between pins with nonsequential behavior. The related pin in a

timing arc is used for the timing check.

No-Change Timing Arcs

This feature models the timing requirement of latch devices with latch-enable signals. The

four no-change timing types define the pulse waveforms of both the constrained signal and

the related signal in standard CMOS and nonlinear CMOS delay models. The information is

used in static timing verification during synthesis.

nochange_high_high (positive/positive)

Indicates a positive pulse on the constrained pin and a positive pulse on

the related pin.

nochange_high_low (positive/negative)

Indicates a positive pulse on the constrained pin and a negative pulse on

the related pin.

nochange_low_high (negative/positive)

Indicates a negative pulse on the constrained pin and a positive pulse on

the related pin.

nochange_low_low (negative/negative)

Indicates a negative pulse on the constrained pin and a negative pulse on

the related pin.

wave_rise_sampling_index and wave_fall_sampling_index Attributes

The wave_rise_sampling_index and wave_fall_sampling_index simple

attributes override the default behavior of the wave_rise and wave_fall attributes

(which select the first and the last vectors to define the sensitization patterns of the input to

the output pin transition that are predefined inside the sensitization template specified at the

library level).

Syntax

wave_rise_sampling_index : integer ;

wave_fall_sampling_index : integer ;

Example

wave_rise (2, 5, 7, 6); /* wave_rise ( wave_rise[0],

wave_rise[1], wave_rise[2], wave_rise[3] );*/

In the previous example, the wave rise vector delay is measured from the last transition

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(vector 7 changing to vector 6) to the output transition. The default

wave_rise_sampling_index value is the last entry in the vector, which is 3 in this case

(because the numbering begins at 0).

To override this default, set the wave_rise_sampling_index attribute, as shown:

wave_rise_sampling_index : 2 ;

When you do this, the delay is measured from the second last transition of the sensitization

vector to the final output transition, in other words from the transition of vector 5 to vector 7.

Note:

You will get an error if you specify a value of 0 for the wave_rise_sampling_index

attribute.

when Simple Attribute

The when attribute is used in state-dependent timing and conditional timing checks.

Note:

The when attribute also appears in the min_pulse_width group and the

minimum_period group (described on and , respectively). Both groups can be placed in

pin, bus, and bundle groups. The when attribute also appears in the power,

fall_power, and rise_power groups.

Syntax

when : "Boolean expression" ;

Boolean expression

A Boolean expression containing names of input, output, inout, and internal

pins.

Example

when : "CD * SD" ;

State-Dependent Timing

In the timing group of a technology library, you can specify state-dependent delays that

correspond to entries in OVI SDF 2.1 syntax. In state-dependent timing, the when attribute

defines a conditional expression on which a timing arc is dependent to activate a path.

Conditional Timing Check

In a conditional timing check, the when attribute defines check-enabling conditions for

timing checks such as setup, hold, and recovery.

Conditional Timing Check in VITAL Models

The when attribute is used in modeling timing check conditions for VITAL models, where, if

you define when, you must also define sdf_cond.

Syntax

when : "Boolean expression" ;

Boolean expression

A valid logic expression as defined in Table 3-3.

Example

when : "CLR & PRE" ;

sdf_cond : "CLR & PRE" ;

when_end Simple Attribute

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The when_end attribute defines a timing-check condition specific to the end event in VHDL

models.

Syntax

when_end : "Boolean expression" ;

Boolean expression

A Boolean expression containing names of input, output, inout, and internal

pins.

Example

when_end : "CD * SD * Q’" ;

when_start Simple Attribute

The when_start attribute defines a timing-check condition specific to the start event in

VHDL models.

Syntax

when_start : "Boolean expression" ;

Boolean expression

A Boolean expression containing the names of input, output, inout, and

internal pins.

Example

when_start : "CD * SD" ;

fall_delay_intercept Complex Attribute

For piecewise models only, the fall_delay_intercept attribute defines the intercept

for vendors using slope- or intercept-type timing equations. The value of the attribute is

added to the falling edge in the delay equation.

Syntax

fall_delay_intercept ("integer, float") ;

Examples from a CMOS library:

fall_delay_intercept (0,"1.0") ; /* piece 0 */

fall_delay_intercept (1,"0.0") ; /* piece 1 */

fall_delay_intercept (2,"-1.0") ; /* piece 2 */

fall_pin_resistance Complex Attribute

For piecewise models only, the fall_pin_resistance attribute defines the drive

resistance applied to pin loads in the falling edge in the transition delay equation.

Syntax

fall_pin_resistance (integer, "float") ;

Examples From a CMOS library:

fall_pin_resistance (0,"0.25") ; /* piece 0 */

fall_pin_resistance (1,"0.50") ; /* piece 1 */

fall_pin_resistance (2,"1.00") ; /* piece 2 */

mode Complex Attribute

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You define the mode attribute within a timing group. A mode attribute pertains to an

individual timing arc. The timing arc is active when mode is instantiated with a name and a

value. You can specify multiple instances of the mode attribute, but only one instance for

each timing arc.

Syntax

mode (mode_name, mode_value);

Example

timing() {

mode(rw, read);

}

Example 3-9 shows a mode description.

Example 3-9 A mode Description

pin(my_outpin) {

direction : output;

timing() {

related_pin : b;

timing_sense : non_unate;

mode(rw, read);

cell_rise(delay3x3) {

values("1.1, 1.2, 1.3", "2.0, 3.0, 4.0", "2.5, 3.5, 4.5");

}

rise_transition(delay3x3) {

values("1.0, 1.1, 1.2", "1.5, 1.8, 2.0", "2.5, 3.0, 3.5");

}

cell_fall(delay3x3) {

values("1.1, 1.2, 1.3", "2.0, 3.0, 4.0", "2.5, 3.5, 4.5");

}

fall_transition(delay3x3) {

values("1.0, 1.1, 1.2", "1.5, 1.8, 2.0", "2.5, 3.0, 3.5");

}

Example 3-10 shows multiple mode descriptions.

Example 3-10 Multiple mode Descriptions

library (MODE_EXAMPLE) {

delay_model : "table_lookup";

time_unit : "1ns";

voltage_unit : "1V";

current_unit : "1mA";

pulling_resistance_unit : "1kohm";

leakage_power_unit : "1nW" ;

capacitive_load_unit (1, pf);

nom_process : 1.0;

nom_voltage : 1.0;

nom_temperature : 125.0;

slew_lower_threshold_pct_rise : 10 ;

slew_upper_threshold_pct_rise : 90 ;

input_threshold_pct_fall : 50 ;

output_threshold_pct_fall : 50 ;

input_threshold_pct_rise : 50 ;

output_threshold_pct_rise : 50 ;

slew_lower_threshold_pct_fall : 10 ;

slew_upper_threshold_pct_fall : 90 ;

slew_derate_from_library : 1.0 ;

cell (mode_example) {

mode_definition(RAM_MODE) {

mode_value(MODE_1) {

}

mode_value(MODE_2) {

}

mode_value(MODE_3) {

}

mode_value(MODE_4) {

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}

interface_timing : true;

dont_use : true;

dont_touch : true;

pin(Q) {

direction : output;

max_capacitance : 2.0;

three_state : "!OE";

timing() {

related_pin : "CK";

timing_sense : non_unate

timing_type : rising_edge

mode(RAM_MODE,"MODE_1 MODE_2");

cell_rise(scalar) {

values( " 0.0 ");

}

cell_fall(scalar) {

values( " 0.0 ");

}

rise_transition(scalar) {

values( " 0.0 ");

}

fall_transition(scalar) {

values( " 0.0 ");

}

timing() {

related_pin : "OE";

timing_sense : positive_unate

timing_type : three_state_enable

mode(RAM_MODE, " MODE_2 MODE_3");

cell_rise(scalar) {

values( " 0.0 ");

}

cell_fall(scalar) {

values( " 0.0 ");

}

rise_transition(scalar) {

values( " 0.0 ");

}

fall_transition(scalar) {

values( " 0.0 ");

}

timing() {

related_pin : "OE";

timing_sense : negative_unate

timing_type : three_state_disable

mode(RAM_MODE, MODE_3);

cell_rise(scalar) {

values( " 0.0 ");

}

cell_fall(scalar) {

values( " 0.0 ");

}

rise_transition(scalar) {

values( " 0.0 ");

}

fall_transition(scalar) {

values( " 0.0 ");

}

pin(A) {

direction : input;

capacitance : 1.0;

max_transition : 2.0;

timing() {

timing_type : setup_rising;

related_pin : "CK";

mode(RAM_MODE, MODE_2);

rise_constraint(scalar) {

values( " 0.0 ");

}

fall_constraint(scalar) {

values( " 0.0 ");

}

timing() {

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timing_type : hold_rising;

related_pin : "CK";

mode(RAM_MODE, MODE_2);

rise_constraint(scalar) {

values( " 0.0 ");

}

fall_constraint(scalar) {

values( " 0.0 ");

}

pin(OE) {

direction : input;

capacitance : 1.0;

max_transition : 2.0;

}

pin(CS) {

direction : input;

capacitance : 1.0;

max_transition : 2.0;

timing() {

timing_type : setup_rising;

related_pin : "CK";

mode(RAM_MODE, MODE_1);

rise_constraint(scalar) {

values( " 0.0 ");

}

fall_constraint(scalar) {

values( " 0.0 ");

}

timing() {

timing_type : hold_rising;

related_pin : "CK";

mode(RAM_MODE, MODE_1);

rise_constraint(scalar) {

values( " 0.0 ");

}

fall_constraint(scalar) {

values( " 0.0 ");

}

pin(CK) {

timing() {

timing_type : "min_pulse_width";

related_pin : "CK";

mode(RAM_MODE , MODE_4);

fall_constraint(scalar) {

values( " 0.0 ");

}

rise_constraint(scalar) {

values( " 0.0 ");

}

timing() {

timing_type : "minimum_period";

related_pin : "CK";

mode(RAM_MODE , MODE_4);

rise_constraint(scalar) {

values( " 0.0 ");

}

fall_constraint(scalar) {

values( " 0.0 ");

}

clock : true;

direction : input;

capacitance : 1.0;

max_transition : 1.0;

}

cell_leakage_power : 0.0;

}

pin_name_map Complex Attribute

Similar to the pin_name_map attribute defined in the cell level, the timing-arc

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pin_name_map attribute defines pin names used to generate stimulus for the current

timing arc. The attribute is optional when pin_name_map pin names are the same as

(listed in order of priority)

1. pin names in the sensitization_master of the current timing arc.

2. pin names in the pin_name_map attribute of the current cell group.

3. pin names in the sensitization_master of the current cell group.

The pin_name_map attribute is required when pin_name_map pin names are different

from all of the pin names in the previous list.

Syntax

pin_name_map (string..., string);

Example

pin_name_map (CIN0, CIN1, CK, Z);

rise_delay_intercept Complex Attribute

For piecewise models only, the rise_delay_intercept attribute defines the intercept

for vendors using slope- or intercept-type timing equations. The value of the attribute is

added to the rising edge in the delay equation.

Syntax

rise_delay_intercept (integer, "float") ;

Examples from a CMOS library:

rise_delay_intercept (0,"1.0") ; /* piece 0 */

rise_delay_intercept (1,"0.0") ; /* piece 1 */

rise_pin_resistance Complex Attribute

For piecewise models only, the rise_pin_resistance attribute defines the drive

resistance applied to pin loads in the rising edge in the transition delay equation.

Syntax

rise_pin_resistance (integer, "float") ;

Examples from a CMOS library:

rise_pin_resistance (0,"0.25"); /* piece 0 */

rise_pin_resistance (1,"0.50"); /* piece 1 */

rise_pin_resistance (2,"1.00"); /* piece 2 */

wave_rise and wave_fall Complex Attributes

The wave_rise and wave_fall attributes represent the two stimuli used in

characterization. The value for both attributes is a list of integer values, and each value is a

vector ID predefined in the library sensitization group. The following example describes the

wave_rise and wave_fall attributes:

wave_rise (vector_id[m]…, vector_id[n]);

wave_fall (vector_id[j]…, vector_id[k]);

Syntax

wave_rise (integer..., integer) ;

wave_fall (integer..., integer) ;

Example

library(my_library) {

…

sensitization(sensi_2in_1out) {

pin_names (IN1, IN2, OUT);

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vector (0, "0 0 0");

vector (1, "0 0 1");

vector (2, "0 1 0");

vector (3, "0 1 1");

vector (4, "1 0 0");

vector (5, "1 0 1");

vector (6, "1 1 0");

vector (7, "1 1 1");

}

cell (my_nand2) {

sensitization_master : sensi_2in_1out;

pin_name_map (A, B, Z); /* these are pin names for the sensitization in this

cell. */

…

pin(A) {

…

}

Pin(B) {

…

}

pin(Z) {

…

timing() {

related_pin : "A";

wave_rise (6, 3); /* 6, 3 - vector id in sensi_2in_1out sensitization

group. Wave form interpretation of the wave_rise is (for "A,

B, Z" pins): 10 1 01 */

wave_fall (3, 6);

…

}

timing() {

related_pin : "B";

wave_rise (7, 4); /* 7, 4 - vector id in sensi_2in_1out sensitization

group. */

wave_fall (4, 7);

…

}

} /* end pin(Z)*/

} /* end cell(my_nand2) */

…

} /* end library */

wave_rise_time_interval and wave_fall_time_interval Complex Attributes

The wave_rise_time_interval and wave_fall_time_interval complex attributes

control the time interval between transitions. By default, the stimuli (specified in

wave_rise and wave_fall) are widely spaced apart during characterization (for

example, 10 ns from one vector to the next) to allow all output transition to stabilize. The

attributes allow you to specify a short duration between one vector to the next in order to

characterize special purpose cells and pessimistic timing characterization.

The wave_rise_time_interval and wave_fall_time_interval attributes are

optional when the default time interval is used for all transitions, and they are required when

you need to define special time intervals between transitions. Usually, the special time

interval is smaller than the default time interval.

The wave_rise_time_interval and wave_fall_time_interval attributes can

have an argument count from 1 to n -1, where n is the number of arguments in

corresponding wave_rise or wave_fall. Use 0 to imply the default time interval used

between vectors.

Syntax

wave_rise_time_interval (float..., float) ;

wave_fall_time_interval (float..., float) ;

Example

wave_rise (2, 5, 7, 6); /* wave_rise ( wave_rise[0],

wave_rise[1], wave_rise[2], wave_rise[3] );*/

wave_rise_time_interval (0.0, 0.3);

The previous example suggests the following:

● Use the default time interval between wave_rise[0] and wave_rise[1] (in

other words, vector 2 and vector 5).

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● Use 0.3 between wave_rise[1] and wave_rise[2] (in other words, vector 5

and vector 7).

● Use the default time interval between wave_rise[2] and wave_rise[3] in

other words, vector 7 and vector 6).

cell_degradation Group

The cell_degradation group describes a cell performance degradation design rule for

compiling a design. A cell degradation design rule specifies the maximum capacitive load a

cell can drive without causing cell performance degradation during the fall transition.

Syntax

pin (output pin name) {

timing () {

cell_degradation (template name) {

...cell_degradation description... }

...

}

...

}

Complex Attributes

coefs /* polynomial model */

orders /* polynomial model */

index_1 /* lookup table */

values /* lookup table */

variable_n_range /* polynomial model */

Group

domain

coefs Complex Attribute

Use the coefs attribute to specify a list of the coefficients you use in a polynomial to

characterize timing information. This attribute is required when you specify a scalable

polynomial delay model. The coefficients are represented in the .lib file and saved in the

database in column-first order. If any is term missing in the polynomial, you must insert a 0

(zero) in the corresponding position in the coefs attribute to ensure correct processing of

the coefficients.

Note:

For a piecewise polynomial, define the coefs attribute inside the domain group inside the

timing group that defines the range of coefficients.

Syntax

pin (output_pin_name) {

timing () {

...

coefs("float, ..., float")

...

}

...

}

Example

timing () {

coefs ("1.0, 2.0, 3.0, 4.0. 5.0, 6.0, 7.0, 8.0, 9.0,

10.0, 11.0, 12.0") ;

}

orders Complex Attribute

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Use the orders attribute to specify the order of the variables you use in a polynomial to

characterize timing information. This attribute is required in the timing group when you

specify a scalable polynomial delay model. The timing group can be any timing group

using polynomial delay modeling.

Note:

For a piecewise polynomial, define the orders attribute inside the domain group inside

the timing group.

Syntax

pin (output_pin_name) {

timing () {

orders("integer, ..., integer")

...

}

...

}

Example

timing () {

orders("2, 1, 1") ;

...

}

variable_n_range Complex Attribute

Use the variable_n_range attribute to specify the order of the variables for the

polynomial to characterize timing information. This attribute is required in the timing group

when you specify a scalable polynomial delay model. The timing group can be any timing

group using polynomial delay modeling.

Note:

For a piecewise polynomial, define the orders attribute inside the domain group inside

the timing group.

Syntax

pin (output_pin_name) {

timing () {

...

variable_n_range(float, float) ;

}

...

}

Example

timing () {

variable_n_range () ;

}

domain Group

In the case of a piecewise polynomial and multiple tables defined by the calc_mode

attribute, use one or more domain groups in the timing group to specify subsets of the

polynomial template and tables of the lookup table templates.

Note:

For a piecewise polynomial, define the orders and coefs attributes inside the domain

group inside the timing group.

If the table is specified by calc_mode, the values attribute must be used inside the

timing group. You can also use the calc_mode and values attributes inside the

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timing group to override the template values.

Note:

A domain name is required.

Syntax

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

domain (namestring){

... domain description...

}

Simple Attribute

calc_mode

Complex Attributes

coefs

orders

variable_n_range

For information about the syntax and usage of the above attributes see the

“cell_degradation Group ” .

Example 3-11 Specifying cell_degradation in a Lookup Table

pin (Z) {

timing () {

cell_degradation (constraint) {

index_1 ("1.0, 1.5, 2.0") ;

values ("1.0, 1.5, 2.0") ;

}

...

}

...

}

Example 3-12 Specifying cell_degradation in a Polynomial

domain (D1) {

orders ("2, 1, 1");

coefs ("1.000, 2.000, 3.000, 4.000, 5.000, 6.000, 7.000,

8.000, 9.000, 10.000, 11.000, 12.000" );

variable_1_range (0.01, 3.00);

variable_2_range (0.01, 3.00);

}

cell_fall Group

The cell_fall group defines cell delay lookup tables (independently of transition delay)

in CMOS nonlinear timing models.

Note:

The same k-factors that scale the cell_fall and cell_rise values also scale the

retaining_fall and retaining_rise values. There are no separate k-factors for the

retaining_fall and retaining_rise values.

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The cell_fall group is defined at the timing group level, as shown here:

Syntax

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

cell_fall (namestring){

... cell fall description...

}

Complex Attributes

index_1 ("float, ..., float");

index_2 ("float, ..., float");

index_3 ("float, ..., float");

values ("float, ..., float", ..., "float, ...,float");

Group

domain

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

Examples from a CMOS library:

cell_fall (cell_template) {

values ("0.00, 0.24", "0.15, 0.26") ;

}

cell_fall (cell_template) {

values ("0.00, 0.33", "0.11, 0.38") ;

}

Each lookup table has an associated string name to indicate which lu_table_template

in the library group it is to use. The name must be the same as the string name you

previously defined in the library lu_table_template. For information about the

lu_table_template syntax, see the description in “lu_table_template Group ” .

You can overwrite index_1, index_2, or index_3 in a lookup table, but the overwrite

must occur before the actual definition of values. The number of floating-point numbers for

index_1, index_2, or index_3 must be the same as the number you used in the

lu_table_template.

The delay value of the table is stored in the values complex attribute. It is a list of

nindex_1 floating-point numbers for a one-dimensional table, nindex_1 x nindex_2

floating-point numbers for a two-dimensional table, or nindex_1 x nindex_2 x nindex_3

floating-point numbers for a three-dimensional table.

In a two-dimensional table, nindex_1 and nindex_2 are the size of index_1 and

index_2 of the lu_table_template group. Group together nindex_1 and nindex_2

by using quotation marks (" ").

In a three-dimensional table, nindex_1 x nindex_2 x nindex_3 are the sizes of

index_1, index_2, and index_3 of the lu_table_template group. Group together

nindex_1, nindex_2, and nindex_3 by using quotation marks (" ").

Transition and cell table delay values must be 0.0 or greater. Propagation tables can

contain negative delay values.

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cell_rise Group

The cell_rise group defines cell delay lookup tables (independently of transition delay)

in CMOS nonlinear timing models.

Note:

The same k-factors that scale the cell_fall and cell_rise values also scale the

retaining_fall and retaining_rise values. There are no separate k-factors for the

retaining_fall and retaining_rise values.

Syntax

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

cell_rise (namestring){

... cell rise description ...

}

Complex Attributes

index_1 ("float, ..., float") ;

index_2 ("float, ..., float") ;

index_3 ("float, ..., float");

values ("float, ..., float", ..., "float, ...,float");

Group

domain

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

Examples from a CMOS library

cell_rise(cell_template) {

values("0.00, 0.23", "0.11, 0.28") ;

}

cell_rise(cell_template) {

values("0.00, 0.25", "0.11, 0.28") ;

}

Each lookup table has an associated string name to indicate where in the library group it

is to be used. The name must be the same as the string name you previously defined in the

library lu_table_template. For information about the lu_table_template syntax,

see the description in “lu_table_template Group ” .”

You can overwrite index_1, index_2, or index_3 in a lookup table, but the overwrite

must occur before the actual definition of values. The number of floating-point numbers for

index_1, index_2, or index_3 must be the same as the number you used in the

lu_table_template.

The delay value of the table is stored in a values complex attribute. It is a list of

nindex_1 floating-point numbers for a one-dimensional table, nindex_1 x nindex_2

floating-point numbers for a two-dimensional table, or nindex_1 x nindex_2 x nindex_3

floating-point numbers for a three-dimensional table.

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In a two-dimensional table, nindex_1 and nindex_2 are the sizes of index_1 and

index_2 of the lu_table_template group. Group together nindex_1 and nindex_2

by using quotation marks (" ").

In a three-dimensional table, nindex_1 x nindex_2 x nindex_3 are the sizes of

index_1, index_2, and index_3 of the lu_table_template group. Group together

nindex_1, nindex_2, and nindex_3 by using by quotation marks (" ").

Each group represents a row in the table. The number of floating-point numbers in a group

must equal nindex_2, and the number of groups in the values complex attribute must

equal nindex_1. The floating-point nindex_2 for a one-dimensional table is "1".

Transition and cell table delay values must be 0.0 or greater. Propagation tables can

contain negative delay values.

The index_3 attribute is part of the functionality that supports three-dimensional tables.

compact_ccs_rise and compact_ccs_fall Groups

The compact_ccs_rise and compact_ccs_fall groups define the compact CCS

timing data in the timing arc.

Syntax

compact_ccs_rise (template_name) {

compact_ccs_fall (template_name) {

Example

timing() {

compact_ccs_rise (LTT3) {

base_curves_group : "ctbct1" ;

values ("0.1, 0.5, 0.6, 0.8, 1, 3", \

"0.15, 0.55, 0.65, 0.85, 2, 4", \

"0.2, 0.6, 0.7, 0.9, 3, 2", \

"0.25, 0.65, 0.75, 0.95, 4, 1");

}

compact_ccs_fall (LTT3) {

values ("-0.12, -0.51, 0.61, 0.82, 1, 2", \

"-0.15, -0.55, 0.65, 0.85, 1, 4", \

"-0.24, -0.67, 0.76, 0.95, 3, 4", \

"-0.25, -0.65, 0.75, 0.95, 3, 1");

}

Simple Attribute

base_curves_group

Complex Attribute

values

base_curves_group Simple Attribute

The base_curves_group attribute is optional at this level when base_curves_name is

the same as that defined in the compact_lut_template that is being referenced by the

compact_ccs_rise or compact_ccs_fall group.

Syntax

base_curves_group : "base_curves_name" ;

Example

base_curves_group : "ctbct1" ;

values Complex Attribute

The values attribute defines the compact CCS timing data values. The values are

determined by the index_3 values.

Syntax

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values ("<float>, <float>, ...", "<float>,

<float>,...");

Example

values ("0.1, 0.5, 0.6, 0.8, 1, 3", \

"0.15, 0.55, 0.65, 0.85, 2, 4", \

"0.2, 0.6, 0.7, 0.9, 3, 2", \

"0.25, 0.65, 0.75, 0.95, 4, 1");

fall_constraint Group

With the rise_constraint group, the fall_constraint group defines timing

constraints (cell delay lookup tables) sensitive to clock or data input transition times. These

constraint tables take the place of the intrinsic_rise and intrinsic_fall attributes

used in other delay models.

The fall_constraint group is defined in a timing group, as shown here:

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

fall_constraint (namestring){

... fall constraint description...

}

Complex Attributes

index_1 ("float, ..., float");

index_2 ("float, ..., float");

index_3 ("float, ..., float");

values ("float, ..., float", ..., "float, ...,float");

Group

domain

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

Example

fall_constraint(constraint_template) {

values ("0.0, 0.14, 0.20", \

"0.22, 0.24, 0.42", \

"0.34, 0.38, 0.51");

}

...

rise_constraint(constraint_template) {

values ("0.0, 0.13, 0.19", \

"0.21, 0.23, 0.41", \

"0.33, 0.37, 0.50");

}

Example 3-13 shows constraint in a timing model.

fall_propagation Group

With the rise_propagation group, the fall_propagation group specifies transition

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delay as a term in the total cell delay.

The fall_propagation group is defined in the timing group, as shown here.

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

fall_propagation (namestring){

... fall propagation description...

}

Complex Attributes

index_1 ("float, ..., float");

index_2 ("float, ..., float");

index_3 ("float, ..., float");

values ("float, ..., float", ..., "float, ...,float");

Group

domain

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

Example

fall_propagation (prop_template) {

values ("0.02, 0.15", "0.12, 0.30") ;

}

rise_propagation (prop_template) {

values ("0.04, 0.20", "0.17, 0.35") ;

}

fall_transition Group

The fall_transition group is defined in the timing group, as shown here:

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

fall_transition (namestring){

... values description...

}

Complex Attributes

index_1 ("float, ..., float");

index_2 ("float, ..., float");

index_3 ("float, ..., float");

values ("float, ..., float", ..., "float, ...,float");

intermediate_values (”float, ..., float”, ..., ”float,

...,float”);

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Note:

As an option, you can use the intermediate_values table attribute to specify the

transition from the first slew point to the output delay threshold. The

intermediate_values table attribute has to use the same format as the table attribute.

Group

domain

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

Example

fall_transition(tran_template) {

values ("0.01, 0.11, 0.18, 0.40");

}

noise_immunity_above_high Group

Use this optional group to describe a noise immunity curve when the input is high and the

noise is over the high voltage rail.

You define the noise_immunity_above_high group in a timing group, as shown here:

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

noise_immunity_above_high (template_namestring){

... values description...

}

template_name

The name of a noise_lut_template group or a poly_template group.

Complex Attributes

coefs /* scalable polynomial only */

orders /* scalable polynomial only */

values /* lookup table only */

Group

domain /* scalable polynomial only */

coefs Complex Attribute

Use the coefs attribute to specify a list of the coefficients you use in a polynomial to

characterize noise immunity information. This attribute is required in the

noise_immunity_above_high group when you specify a scalable polynomial model.

The coefficients are represented in the .lib file and saved in the database in column-first

order. If any term is missing in the polynomial, you must insert a 0 (zero) in the

corresponding position in the coefs attribute to ensure correct processing of the

coefficients.

Note:

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For a piecewise polynomial, the coefs attribute must be defined inside the domain group

inside the noise_immunity_above_high group that defines the range of coefficients.

Syntax

pin (input_pin_name) {

timing () {

noise_immunity_above_high (poly_template_namestring){

coefs("float, ..., float")

}

...

}

orders Complex Attribute

Use the orders attribute to specify the order for the variables for the polynomial to

characterize noise immunity information. This attribute is required in the

noise_immunity_above_high group when you specify a scalable polynomial model.

Note:

For a piecewise polynomial, define the orders attribute inside the domain group inside

the noise_immunity_above_high group.

Syntax

pin (input_pin_name) {

timing () {

noise_immunity_above_high (poly_template_namestring){

orders("integer, ..., integer")

}

...

}

Example

pin (Z) {

timing () {

noise_immunity_above_high (){

orders("2, 1, 1") ;

coefs ("1.0, 2.0, 3.0, 4.0. 5.0, 6.0, 7.0, 8.0, 9.0,

10.0, 11.0, 12.0") ;

}

...

}

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

noise_immunity_below_low Group

Use this optional group to describe a noise immunity curve when the input is low and the

noise is below the low voltage rail.

For information about the noise_immunity_below_low group syntax and attributes, see

“noise_immunity_above_high Group” .

noise_immunity_high Group

Use this optional group to describe a noise immunity curve when the input is high and the

noise is below the high voltage rail.

For information about the noise_immunity_high group syntax and attributes, see

“noise_immunity_above_high Group” .

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noise_immunity_low Group

Use this optional group to describe a noise immunity curve when the input is low and the

noise is over the low voltage rail.

For information about the noise_immunity_low group syntax and attributes, see

“noise_immunity_above_high Group” .

output_current_fall Group

Use the output_current_fall and the output_current_rise groups to specify the

output current for a nonlinear lookup table model.

The output_current_fall group is defined in the timing group, as shown here.

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

output_current_fall (namestring){

... description ...

}

Groups

vector

vector Group

Use the vector group to store information about the input slew and output load.

The vector group is defined in the output_current_fall group, as shown here.

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

output_current_fall (namestring){

vector () {

... description ...

}

Simple Attribute

reference_time

reference_time Simple Attribute

Use the reference_time attribute to specify the time at which the input wave form

crosses the rising or falling input delay threshold.

The reference_time attribute is defined in the vector group, as shown here.

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

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output_current_fall (namestring){

vector () {

reference_time : ;

}

Example

timing () {

output_current_rise () {

vector (CCT) {

reference_time : 0.05 ;

index_1 (0.1) ;

index_1 (1.1) ;

index_1 (1, 3, 3, 4, 5) ;

values ( 1.1, 1.3, 1.5, 1.2, 1.4) ;

}

output_current_rise Group

For information about using the output_current_rise group, see the definition of the

“output_current_fall Group ” .

propagated_noise_height_above_high Group

Use this group to describe noise propagation through a cell when the input is high and the

noise is over the high voltage rail.

You define the propagated_noise_above_high group in a timing group, as shown

here:

...

timing () {

propagated_noise_height_above_high (template_namestring){

... values description...

}

template_name

The name of a propagation_lut_template group or a

poly_template group.

Complex Attributes

coefs /* scalable polynomial only */

orders /* scalable polynomial only */

values /* lookup table only */

Group

domain /* scalable polynomial only */

coefs Complex Attribute

Use the coefs attribute to specify a list of the coefficients you use in a polynomial to

characterize propagated noise information. This attribute is required in the

propagated_noise_height_above_high group when you specify a scalable

polynomial model. The coefficients are represented in the .lib file and saved in the database

in column-first order. If any term is missing in the polynomial, you must insert a 0 (zero) in

the corresponding position in the coefs attribute to ensure correct processing of the

coefficients.

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Note:

For a piecewise polynomial, define the coefs attribute inside the domain group inside the

propagated_noise_height_above_high group that defines the range of coefficients.

Syntax

pin (input_pin_nameid) {

timing () {

propagated_noise_height_above_high \

(poly_template_nameid){

coefs("float, ..., float")

}

...

}

orders Complex Attribute

Use the orders attribute to specify the order of the variables for the polynomial to

characterize noise immunity information. This attribute is required in the

propagated_noise_height_above_high group when you specify a scalable

polynomial model. For a piecewise polynomial, the orders attribute should be used inside

the domain group inside the propagated_noise_height_above_high group.

Syntax

pin (input_pin_name) {

timing () {

propagated_noise_height_above_high \

(poly_template_namestring){

orders("integer, ..., integer")

}

...

}

Example

pin (Z) {

timing () {

orders("2, 1, 1") ;

coefs ("1.0, 2.0, 3.0, 4.0. 5.0, 6.0, 7.0, 8.0, 9.0,

10.0, 11.0, 12.0") ;

}

...

}

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

propagated_noise_height_below_low Group

Use this group to describe noise propagation through a cell when the input is low and the

noise is below the low voltage rail.

For information about the propagated_noise_height_below_low group syntax and

attributes, see “propagated_noise_height_above_high Group” .

propagated_noise_height_high Group

Use this group to describe noise propagation through a cell when the input is high and the

noise is below the high voltage rail.

For information about the propagated_noise_height_high group syntax and

attributes, see “propagated_noise_height_above_high Group” .

propagated_noise_height_low Group

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Use this group to describe noise propagation through a cell when the input is low and the

noise is over the low voltage rail.

For information about the propagated_noise_height_low group syntax and attributes,

see “propagated_noise_height_above_high Group” .

propagated_noise_peak_time_ratio_above_high Group

Use this group to describe noise propagation through a cell when the input is high and the

noise is over the high voltage rail.

For information about the propagated_noise_peak_time_ratio_above_high group

syntax and attributes, see “propagated_noise_height_above_high Group” .

propagated_noise_peak_time_ratio_below_low Group

Use this group to describe noise propagation through a cell when the input is low and the

noise is below the low voltage rail.

For information about the propagated_noise_peak_time_ratio_below_low group

syntax and attributes, see “propagated_noise_height_above_high Group” .

propagated_noise_peak_time_ratio_high Group

Use this group to describe noise propagation through a cell when the input is high and the

noise is below the high voltage rail.

For information about the propagated_noise_peak_time_ratio_high group syntax

and attributes, see “propagated_noise_height_above_high Group” .

propagated_noise_peak_time_ratio_low Group

Use this group to describe noise propagation through a cell when the input is low and the

noise is over the low voltage rail.

For information about the propagated_noise_peak_time_ratio_low group syntax

and attributes, see “propagated_noise_height_above_high Group” .

propagated_noise_width_above_high Group

Use this group to describe noise propagation through a cell when the input is high and the

noise is over the high voltage rail.

For information about the propagated_noise_width_above_high group syntax and

attributes, see “propagated_noise_height_above_high Group” .

propagated_noise_width_below_low Group

Use this group to describe noise propagation through a cell when the input is low and the

noise is below the low voltage rail.

For information about the propagated_noise_width_below_low group syntax and

attributes, see “propagated_noise_height_above_high Group” .

propagated_noise_width_high Group

Use this group to describe noise propagation through a cell when the input is high and the

noise is below the high voltage rail.

For information about the propagated_noise_width_high group syntax and attributes,

see “propagated_noise_height_above_high Group” .

propagated_noise_width_low Group

Use this group to describe noise propagation through a cell when the input is low and the

noise is over the low voltage rail.

For information about the propagated_noise_width_low group syntax and attributes,

see “propagated_noise_height_above_high Group” .

receiver_capacitance1_fall Group

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You can define the receiver_capacitance1_fall group at the pin level and at the timing level.

Define the receiver_capacitance1_fall group at the timing level to specify receiver

capacitance for a timing arc. For information about using the group at the pin level, see

“receiver_capacitance1_fall Group” .

Syntax

receiver_capacitance1_fall (value) {

Complex Attribute

values

Example

timing() {

...

receiver_capacitance1_fall () {

values (“2.0, 4.0, 1.0, 3.0”) ;

}

receiver_capacitance1_rise Group

For information about using the receiver_capacitance1_rise group, see the

description of the receiver_capacitance1_fall Group.

receiver_capacitance2_fall Group

For information about using the receiver_capacitance2_fall group, see the

description of receiver_capacitance1_fall Group.

receiver_capacitance2_rise Group

For information about using the receiver_capacitance2_rise group, see the

description of the receiver_capacitance1_fall Group.

retaining_fall Group

The retaining_fall group specifies the length of time the output port retains its current

logical value of 1 after the output port’s corresponding input port’s value has changed.

This attribute is used only with nonlinear delay models.

Note:

The same k-factors that scale the cell_fall and cell_rise values also scale the

retaining_fall and retaining_rise values. There are no separate k-factors for the

retaining_fall and retaining_rise values.

Syntax

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

retaining_fall (namestring){

... retaining fall description ...

}

Complex Attributes

index_1 ("float, ..., float");

index_2 ("float, ..., float");

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index_3 ("float, ..., float");

values ("float, ..., float", "float, ...,float" , "float, ...,float");

Group

domain

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

Example

retaining_rise (retaining_table_template) {

values ("0.00, 0.23", "0.11, 0.28") ;

}

retaining_fall (retaining_table_template) {

values ("0.01, 0.30", "0.12, 0.18") ;

}

retaining_rise Group

The retaining_rise group specifies the length of time an output port retains its current

logical value of 0 after the output port’s corresponding input port’s value has changed.

This attribute is used only with nonlinear delay models.

Note:

The same k-factors that scale the cell_fall and cell_rise values also scale the

retaining_fall and retaining_rise values. There are no separate k-factors for the

retaining_fall and retaining_rise values.

Syntax

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

retaining_rise (namestring){

... retaining rise description ...

}

Complex Attributes

index_1 ("float, ..., float");

index_2 ("float, ..., float");

index_3 ("float, ..., float");

values ("float, ..., float", "float, ...,float", "float,

...,float");

Group

domain

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

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Example

retaining_rise (retaining_table_template) {

values ("0.00, 0.23", "0.11, 0.28") ;

}

retaining_fall (retaining_table_template) {

values ("0.01, 0.30", "0.12, 0.18") ;

}

retain_fall_slew Group

Use this group in the timing group to define a slew table associated with the

retaining_fall delay. The slew table describes the rate of decay of the output logic

value.

Syntax

retain_fall_slew (retaining_time_templatestring) {

values (index1float, index2float, index3float) ;

}

retain_fall_slew (retaining_time_templatestring) {

orders("variable1integer, variable2integer") ;

coefs("coefficient_1float, ..., coefficient_nfloat")

variable_n_range(float, float) ;

}

retaining_time_template

Name of the table template to use for the lookup table.

index1 , index2 , index3

Values to use for indexing the lookup table.

variable1, variable2

The orders of the variables for the polynomial.

coefficient_1 , ..., coefficient_n

Specifies the coefficients used in the polynomial to characterize timing

information.

Examples

cell (cell_name) {

...

pin (pin_name) {

direction : output :

...

timing ( ) {

related_pin : "related_pin" ;

...

retaining_fall (retaining_table_template) {

values ( "0.00, 0.23", "0.11, 0.28") ;

}

...

retain_fall_slew (retaining_time_template) {

values ( "0.01, 0.02" ) ;

}

...

}

cell (cell_name) {

...

pin (pin_name) {

direction : output :

...

timing ( ) {

related_pin : "related_pin" ;

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...

retaining_fall (retaining_table_template) {

orders ("1, 1");

coefs ("0.2407, 3.1568, 0.0129, 0.0143") ;

variable_1_range (0.01, 3.00);

variable_2_range (0.01, 3.00);

}

...

retain_fall_slew (retaining_time_template) {

orders ("1, 1");

coefs ("0.2407, 3.1568, 0.0129, 0.0143") ;

variable_1_range (0.01, 3.00);

variable_2_range (0.01, 3.00);

}

...

}

retain_rise_slew Group

Use this group in the timing group to define a slew table associated with the

retaining_rise delay. The slew table describes the rate of decay of the output logic

value.

Syntax

retain_rise_slew (retaining_time_templatestring) {

values(index1float, index2float, index3float) ;

}

retain_rise_slew (retaining_time_templatestring) {

orders("variable1integer, variable2integer") ;

coefs("coefficient_1float, ..., coefficient_nfloat")

variable_n_range(float, float) ;

}

retaining_time_template

Name of the table template to use for the lookup table.

index1float , index2float , index3float

Values to use for indexing the lookup table.

variable1, variable2

The orders of the variables for the polynomial.

coefficient_1float , ..., coefficient_nfloat

Specifies the coefficients used in the polynomial to characterize timing

information.

Examples

cell (cell_name) {

...

pin (pin_name) {

direction : output :

...

timing ( ) {

related_pin : "related_pin"

...

retaining_rise (retaining_table_template) {

values ( "0.00, 0.23", "0.11, 0.28") ;

}

...

retain_rise_slew (retaining_time_template) {

values ( "0.01, 0.02" ) ;

}

...

}

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cell (cell_name) {

...

pin (pin_name) {

direction : output :

...

timing ( ) {

related_pin : "related_pin"

...

retaining_rise (retaining_table_template) {

orders ("1, 1");

coefs ("0.2407, 3.1568, 0.0129, 0.0143") ;

variable_1_range (0.01, 3.00);

variable_2_range (0.01, 3.00);

}

...

retain_rise_slew (retaining_time_template) {

orders ("1, 1");

coefs ("0.2407, 3.1568, 0.0129, 0.0143") ;

variable_1_range (0.01, 3.00);

variable_2_range (0.01, 3.00);

}

...

}

rise_constraint Group

With the fall_constraint group, the rise_constraint group defines timing

constraints (cell delay lookup tables) sensitive to clock or data input transition times. These

constraint tables take the place of the intrinsic_rise and intrinsic_fall attributes

used in the other delay models.

Syntax

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

rise_constraint (namestring){

... values description...

}

Complex Attributes

index_1 ("float, ..., float");

index_2 ("float, ..., float");

index_3 ("float, ..., float");

values ("float, ..., float", ..., "float, ...,float");

Group

domain

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

Example

rise_constraint(constraint_template) {

values ("0.0, 0.13, 0.19", \

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"0.21, 0.23, 0.41", \

"0.33, 0.37, 0.50");

}

Example 3-13 shows constraints in a timing model.

Example 3-13 CMOS Nonlinear Timing Model Using Constraints

library( vendor_b ) {

/* 1. Use delay lookup table */

delay_model : table_lookup;

/* 2. Define template of size 3 x 3*/

lu_table_template(constraint_template) {

variable_1 : constrained_pin_transition;

variable_2 : related_pin_transition;

index_1 ("0.0, 0.5, 1.5");

index_2 ("0.0, 2.0, 4.0");

}

...

cell(dff) {

pin(d) {

direction: input;

timing( "t1" | "t1", "t2", "t3" ) {

related_pin : "clk";

timing_type : setup_rising;

...

/* Inherit the ’constraint_template’ template */

rise_constraint(constraint_template) {

/* Specify all the values */

values ("0.0, 0.13, 0.19", \

"0.21, 0.23, 0.41", \

"0.33, 0.37, 0.50");

}

fall_constraint(constraint_template) {

values ("0.0, 0.14, 0.20", \

"0.22, 0.24, 0.42", \

"0.34, 0.38, 0.51");

}

rise_propagation Group

With the fall_propagation group, the rise_propagation group specifies transition

delay as a term in the total cell delay.

Syntax

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

rise_propagation (namestring){

... rise propagation description ...

}

Complex Attributes

index_1 ("float, ..., float");

index_2 ("float, ..., float");

index_3 ("float, ..., float");

values ("float, ..., float", ..., "float, ...,float");

Group

domain

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domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

Example

fall_propagation (prop_template) {

values("0.00, 0.21", "0.14, 0.38") ;

}

rise_propagation (prop_template) {

values("0.05, 0.25", "0.15, 0.48") ;

}

rise_transition Group

The rise_transition group is defined in the timing group, as shown here:

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

rise_transition (namestring){

... rise transition description ...

}

Complex Attributes

index_1 ("float, ..., float");

index_2 ("float, ..., float");

index_3 ("float, ..., float");

values ("float, ..., float", ..., "float, ...,float");

intermediate_values (”float, ..., float”, ..., ”float,

...,float”);

Note:

Optionally, you can use the intermediate_values table attribute to specify the

transition from the first slew point to the output delay threshold. The

intermediate_values table attribute has to use the same format as the table attribute.

Group

domain

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

Examples

rise_transition(tran_template) {

values ("0.01, 0.08, 0.15, 0.40");

}

fall_transition(tran_template) {

values ("0.01, 0.11, 0.18, 0.40");

}

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steady_state_current_high Group

This optional group defines the current-voltage (I-V) characteristic for a cell timing arc by

holding the output signal high.

You define the steady_state_current_high group in a timing group, as shown here:

library (namestring) {

cell (namestring) {

pin (namestring) {

timing () {

steady_state_current_high (template_namestring){

... values description...

}

template_name

The name of an iv_lut_template group or a poly_template group.

Complex Attributes

coefs /* scalable polynomial only */

orders /* scalable polynomial only */

values /* lookup table only */

Group

domain /* scalable polynomial only */

coefs Complex Attribute

Use the coefs attribute to specify a list of the coefficients you use in a polynomial to

characterize steady-state current information. This attribute is required in the

steady_state_current_high group when you specify a scalable polynomial model.

The coefficients are represented in the .lib file and saved in the database in column-first

order. If any term is missing in the polynomial, you must insert a 0 (zero) in the

corresponding position in the coefs attribute to ensure correct processing of the

coefficients.

Note:

For a piecewise polynomial, define the coefs attribute inside the domain group inside the

steady_state_current_high group that defines the range of coefficients.

Syntax

pin (output_pin_name) {

timing () {

steady_state_current_high (poly_templatestring){

coefs("float, ..., float")

}

...

}

orders Complex Attribute

Use the orders attribute to specify the order of the variables for the polynomial to

characterize steady state current information. This attribute is required in the

steady_state_current_high group when you specify a scalable polynomial model.

Note:

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For a piecewise polynomial, define the orders attribute inside the domain group inside

the steady_state_current_high group.

Syntax

pin (output_pin_name) {

timing () {

steady_state_current_high (poly_template_namestring){

orders("integer, ..., integer")

}

...

}

Example

pin (Z) {

timing () {

orders("2, 1, 1") ;

coefs ("1.0, 2.0, 3.0, 4.0. 5.0, 6.0, 7.0, 8.0, 9.0,

10.0, 11.0, 12.0") ;

variable_n_range

}

...

}

Syntax

pin (output_pin_name) {

timing () {

steady_state_current_high (lut_table_templatestring){

orders("integer, ..., integer")

coefs("float, ..., float")

values (integer, integer) ;

}

...

}

Example

pin (Z) {

timing () {

steady_state_current_high (){

values ("2, 1.8, ...-0.8") ;

}

...

}

domain Group

For information about the domain group syntax and usage, see the description in the

“domain Group ” .

steady_state_current_low Group

This optional group defines the current-voltage (I-V) characteristic for a cell timing arc by

holding the output signal low.

Complex Attribute

coefs

orders

values

intermediate_values ("float, ..., float", ..., "float,

...,float");

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Note:

Optionally, you can use the intermediate_values table attribute to specify the

transition from the first slew point to the output delay threshold. The

intermediate_values table attribute has to use the same format as the table attribute.

Group

domain

For information about the steady_state_current_tristate group syntax and

attributes, see “steady_state_current_high Group” .

steady_state_current_tristate Group

This optional group defines the current-voltage (I-V) characteristic for tri-state timing arcs.

Complex Attributes

coefs

orders

values

intermediate_values ("float, ..., float", ..., "float,

...,float");

Note:

Optionally, you can use the intermediate_values table attribute to specify the

transition from the first slew point to the output delay threshold. The

intermediate_values table attribute has to use the same format as the table attribute.

Group

domain

For information about the steady_state_current_tristate group syntax and

attributes, see “steady_state_current_high Group” .

pin_based_variation Group

The pin_based_variation group is similar to the timing_based_variation group

in that it specifies the rising and falling output transitions for variation parameters (by the

va_compact_ccs_rise and va_compact_ccs_fall groups) and specifies variation-

aware receiver capacitance information. If a receiver capacitance group exists in a pin

group, the variation-aware CCS receiver model groups, such as the following, are required

in the pin_based_variation group.

● va_receiver_capacitance1_rise

● va_receiver_capacitance1_fall

● va_receiver_capacitance2_rise

● va_receiver_capacitance2_fall